diff --git a/apps/server/src/agent-tools/tools/tool-input.ts b/apps/server/src/agent-tools/tools/tool-input.ts
index 8159b1c..04d353f 100644
--- a/apps/server/src/agent-tools/tools/tool-input.ts
+++ b/apps/server/src/agent-tools/tools/tool-input.ts
@@ -49,7 +49,7 @@ export function optionalDate(value: unknown, field: string): ToolInputResult<str
     return { ok: false, error: `${field} 必须是 YYYY-MM-DD 日期` };
   }
   const date = new Date(`${value}T00:00:00Z`);
-  if (Number.isNaN(date.getTime()) || dayjs(date).utc().format('YYYY-MM-DD') !== value) {
+  if (Number.isNaN(date.getTime()) || dayjs(date).utcOffset(8).format('YYYY-MM-DD') !== value) {
     return { ok: false, error: `${field} 不是有效日期` };
   }
   return { ok: true, value };
diff --git a/apps/server/src/attendance/attendance-calendar.service.ts b/apps/server/src/attendance/attendance-calendar.service.ts
index 3e73a5a..81f3962 100644
--- a/apps/server/src/attendance/attendance-calendar.service.ts
+++ b/apps/server/src/attendance/attendance-calendar.service.ts
@@ -76,7 +76,7 @@ export class AttendanceCalendarService {
     const start = new Date(weekStart);
     const end = new Date(start);
     end.setDate(start.getDate() + 6);
-    const endStr = dayjs(end).utc().format('YYYY-MM-DD');
+    const endStr = dayjs(end).utcOffset(8).format('YYYY-MM-DD');
 
     const records = await this.attendanceRepo.find({
       where: {
diff --git a/apps/server/src/attendance/attendance-generation.service.ts b/apps/server/src/attendance/attendance-generation.service.ts
index b1dd7cf..b4799ea 100644
--- a/apps/server/src/attendance/attendance-generation.service.ts
+++ b/apps/server/src/attendance/attendance-generation.service.ts
@@ -97,7 +97,7 @@ export class AttendanceGenerationService {
     const entities: AttendanceRecord[] = [];
     const end = new Date(dateTo);
     for (let d = new Date(dateFrom); d <= end; d.setDate(d.getDate() + 1)) {
-      const dateStr = dayjs(d).utc().format('YYYY-MM-DD');
+      const dateStr = dayjs(d).utcOffset(8).format('YYYY-MM-DD');
       const weekDay = d.getDay() === 0 ? 7 : d.getDay();
 
       for (const sched of schedules) {
@@ -158,7 +158,7 @@ export class AttendanceGenerationService {
   }
 
   private getCourseClock(date: Date): { date: string; minutes: number } {
-    const c = dayjs.utc(date).add(8, 'hour');
+    const c = dayjs(date).utcOffset(8);
     return {
       date: c.format('YYYY-MM-DD'),
       minutes: c.hour() * 60 + c.minute(),
diff --git a/apps/server/src/attendance/attendance-import.service.ts b/apps/server/src/attendance/attendance-import.service.ts
index 6b4eabc..d0e07cc 100644
--- a/apps/server/src/attendance/attendance-import.service.ts
+++ b/apps/server/src/attendance/attendance-import.service.ts
@@ -239,7 +239,7 @@ export class AttendanceImportService {
   }
 
   private formatDate(value: Date): string {
-    return dayjs.utc(value).format('YYYY-MM-DD');
+    return dayjs(value).utcOffset(8).format('YYYY-MM-DD');
   }
 
   /**
diff --git a/apps/server/src/attendance/attendance-leave-sync.service.ts b/apps/server/src/attendance/attendance-leave-sync.service.ts
index dd57002..91975e6 100644
--- a/apps/server/src/attendance/attendance-leave-sync.service.ts
+++ b/apps/server/src/attendance/attendance-leave-sync.service.ts
@@ -153,7 +153,7 @@ export class AttendanceLeaveSyncService {
   }
 
   private formatDate(value: Date): string {
-    return dayjs.utc(value).format('YYYY-MM-DD');
+    return dayjs(value).utcOffset(8).format('YYYY-MM-DD');
   }
 
   private async resolveStudentName(dingUserId: string): Promise<string> {
diff --git a/apps/server/src/attendance/attendance-records.controller.ts b/apps/server/src/attendance/attendance-records.controller.ts
index b02e09c..4a6b46f 100644
--- a/apps/server/src/attendance/attendance-records.controller.ts
+++ b/apps/server/src/attendance/attendance-records.controller.ts
@@ -196,11 +196,11 @@ export class AttendanceRecordsController extends AttendanceControllerBase {
         source: record.source || '',
         punchDevice: record.punchDeviceName || record.punchDeviceId || '',
         punchTime: record.punchTime
-          ? dayjs(record.punchTime).utc().format('YYYY-MM-DD HH:mm:ss')
+          ? dayjs(record.punchTime).utcOffset(8).format('YYYY-MM-DD HH:mm:ss')
           : '',
         remark: record.remark || '',
         createdAt: record.createdAt
-          ? dayjs(record.createdAt).utc().format('YYYY-MM-DD HH:mm:ss')
+          ? dayjs(record.createdAt).utcOffset(8).format('YYYY-MM-DD HH:mm:ss')
           : '',
       });
     }
diff --git a/apps/server/src/attendance/attendance-report.service.ts b/apps/server/src/attendance/attendance-report.service.ts
index bed6638..72108e3 100644
--- a/apps/server/src/attendance/attendance-report.service.ts
+++ b/apps/server/src/attendance/attendance-report.service.ts
@@ -142,7 +142,7 @@ export class AttendanceReportService {
   async getAlerts(days: number = 14, threshold: number = 3, accessibleClassIds?: number[]) {
     const cutoff = new Date();
     cutoff.setDate(cutoff.getDate() - days);
-    const cutoffStr = dayjs(cutoff).utc().format('YYYY-MM-DD');
+    const cutoffStr = dayjs(cutoff).utcOffset(8).format('YYYY-MM-DD');
 
     const qb = this.attendanceRepo
       .createQueryBuilder('a')
diff --git a/apps/server/src/attendance/attendance-settlement.service.ts b/apps/server/src/attendance/attendance-settlement.service.ts
index 46f1daf..4d474c9 100644
--- a/apps/server/src/attendance/attendance-settlement.service.ts
+++ b/apps/server/src/attendance/attendance-settlement.service.ts
@@ -285,7 +285,7 @@ export class AttendanceSettlementService {
 
   private getCourseClock(date: Date): { date: string; weekDay: number; minutes: number } {
     // Asia/Shanghai 无夏令时，固定 UTC+8 与 Intl 时区格式化等价
-    const c = dayjs.utc(date).add(8, 'hour');
+    const c = dayjs(date).utcOffset(8);
     const weekDay = c.day() === 0 ? 7 : c.day();
     return {
       date: c.format('YYYY-MM-DD'),
diff --git a/apps/server/src/bills/bills-generation.service.ts b/apps/server/src/bills/bills-generation.service.ts
index a780489..5861fd2 100644
--- a/apps/server/src/bills/bills-generation.service.ts
+++ b/apps/server/src/bills/bills-generation.service.ts
@@ -259,7 +259,7 @@ export class BillsGenerationService {
   private isValidDate(value: string) {
     if (!/^\d{4}-\d{2}-\d{2}$/.test(value || '')) return false;
     const date = new Date(`${value}T00:00:00Z`);
-    return !Number.isNaN(date.getTime()) && dayjs(date).utc().format('YYYY-MM-DD') === value;
+    return !Number.isNaN(date.getTime()) && dayjs(date).utcOffset(8).format('YYYY-MM-DD') === value;
   }
 
 
diff --git a/apps/server/src/classroom-rentals/rental-schedule.service.ts b/apps/server/src/classroom-rentals/rental-schedule.service.ts
index 321ab7b..15cf14f 100644
--- a/apps/server/src/classroom-rentals/rental-schedule.service.ts
+++ b/apps/server/src/classroom-rentals/rental-schedule.service.ts
@@ -135,7 +135,7 @@ export class RentalScheduleService {
     const current = this.toUtcDate(startDate);
     const end = this.toUtcDate(endDate);
     while (current <= end) {
-      dates.add(dayjs(current).utc().format('YYYY-MM-DD'));
+      dates.add(dayjs(current).utcOffset(8).format('YYYY-MM-DD'));
       current.setUTCDate(current.getUTCDate() + 1);
     }
   }
@@ -155,7 +155,7 @@ export class RentalScheduleService {
     const startWeekDay = current.getUTCDay() || 7;
     current.setUTCDate(current.getUTCDate() + ((schedule.weekDay - startWeekDay + 7) % 7));
     while (current <= end) {
-      dates.add(dayjs(current).utc().format('YYYY-MM-DD'));
+      dates.add(dayjs(current).utcOffset(8).format('YYYY-MM-DD'));
       current.setUTCDate(current.getUTCDate() + 7);
     }
   }
diff --git a/apps/server/src/classrooms/classrooms.service.ts b/apps/server/src/classrooms/classrooms.service.ts
index a597402..215062a 100644
--- a/apps/server/src/classrooms/classrooms.service.ts
+++ b/apps/server/src/classrooms/classrooms.service.ts
@@ -392,7 +392,7 @@ export class ClassroomsService {
       const effStart = new Date(Math.max(new Date(r.startDate).getTime(), start.getTime()));
       const effEnd = new Date(Math.min(new Date(r.endDate).getTime(), end.getTime()));
       for (let d = new Date(effStart); d <= effEnd; d.setDate(d.getDate() + 1)) {
-        rentalDaysByRoom[r.classroomId].add(dayjs(d).utc().format('YYYY-MM-DD'));
+        rentalDaysByRoom[r.classroomId].add(dayjs(d).utcOffset(8).format('YYYY-MM-DD'));
       }
     }
 
@@ -401,7 +401,7 @@ export class ClassroomsService {
       const effStart = new Date(Math.max(new Date(s.startDate).getTime(), start.getTime()));
       const effEnd = new Date(Math.min(new Date(s.endDate).getTime(), end.getTime()));
       for (let d = new Date(effStart); d <= effEnd; d.setDate(d.getDate() + 1)) {
-        scheduleDaysByRoom[s.classroomId].add(dayjs(d).utc().format('YYYY-MM-DD'));
+        scheduleDaysByRoom[s.classroomId].add(dayjs(d).utcOffset(8).format('YYYY-MM-DD'));
       }
     }
 
diff --git a/apps/server/src/database/date-normalization.spec.ts b/apps/server/src/database/date-normalization.spec.ts
index a9ff829..df17a24 100644
--- a/apps/server/src/database/date-normalization.spec.ts
+++ b/apps/server/src/database/date-normalization.spec.ts
@@ -5,8 +5,9 @@ describe('normalizeDateOnly', () => {
     expect(normalizeDateOnly('2026-07-02')).toBe('2026-07-02');
   });
 
-  it('converts legacy ISO timestamps to their UTC calendar date', () => {
-    expect(normalizeDateOnly('2026-07-01T16:00:00.000Z')).toBe('2026-07-01');
+  it('converts legacy ISO timestamps to their China calendar date (UTC+8)', () => {
+    // 2026-07-01T16:00:00Z = 北京时间 2026-07-02 00:00
+    expect(normalizeDateOnly('2026-07-01T16:00:00.000Z')).toBe('2026-07-02');
   });
 
   it('rejects unsupported date formats', () => {
diff --git a/apps/server/src/database/date-normalization.ts b/apps/server/src/database/date-normalization.ts
index 5717b61..6d9d65c 100644
--- a/apps/server/src/database/date-normalization.ts
+++ b/apps/server/src/database/date-normalization.ts
@@ -9,7 +9,7 @@ export function normalizeDateOnly(value?: string | null): string | null | undefi
   const isoPrefix = ISO_DATE_PREFIX_PATTERN.exec(value)?.[1];
   if (isoPrefix) {
     const date = new Date(value);
-    if (!Number.isNaN(date.getTime())) return dayjs(date).utc().format('YYYY-MM-DD');
+    if (!Number.isNaN(date.getTime())) return dayjs(date).utcOffset(8).format('YYYY-MM-DD');
   }
 
   throw new Error(`无效日期格式: ${value}`);
diff --git a/apps/server/src/expenses/expense-operations.service.ts b/apps/server/src/expenses/expense-operations.service.ts
index f51c177..d64007a 100644
--- a/apps/server/src/expenses/expense-operations.service.ts
+++ b/apps/server/src/expenses/expense-operations.service.ts
@@ -29,7 +29,7 @@ export class ExpenseOperationsService {
   private isValidDate(value: string) {
     if (!/^\d{4}-\d{2}-\d{2}$/.test(value || '')) return false;
     const date = new Date(`${value}T00:00:00Z`);
-    return !Number.isNaN(date.getTime()) && dayjs(date).utc().format('YYYY-MM-DD') === value;
+    return !Number.isNaN(date.getTime()) && dayjs(date).utcOffset(8).format('YYYY-MM-DD') === value;
   }
 
   async createPersonalExpense(dto: CreatePersonalExpenseDto, userId?: number) {
diff --git a/apps/server/src/expenses/expenses.service.ts b/apps/server/src/expenses/expenses.service.ts
index 53fc9c0..6910942 100644
--- a/apps/server/src/expenses/expenses.service.ts
+++ b/apps/server/src/expenses/expenses.service.ts
@@ -342,7 +342,7 @@ export class ExpensesService {
   private isValidDate(value: string) {
     if (!/^\d{4}-\d{2}-\d{2}$/.test(value || '')) return false;
     const date = new Date(`${value}T00:00:00Z`);
-    return !Number.isNaN(date.getTime()) && dayjs(date).utc().format('YYYY-MM-DD') === value;
+    return !Number.isNaN(date.getTime()) && dayjs(date).utcOffset(8).format('YYYY-MM-DD') === value;
   }
 
   async createStudentUtilityBill(dto: CreateStudentUtilityBillDto, userId?: number) {
diff --git a/apps/server/src/occupancies/occupancy-operations.service.ts b/apps/server/src/occupancies/occupancy-operations.service.ts
index f0c503e..77896ef 100644
--- a/apps/server/src/occupancies/occupancy-operations.service.ts
+++ b/apps/server/src/occupancies/occupancy-operations.service.ts
@@ -159,7 +159,7 @@ export class OccupancyOperationsService {
       const transferDate = new Date(dto.transferDate);
       const nextDay = new Date(transferDate);
       nextDay.setDate(nextDay.getDate() + 1);
-      const defaultBillingStart = dayjs(nextDay).utc().format('YYYY-MM-DD');
+      const defaultBillingStart = dayjs(nextDay).utcOffset(8).format('YYYY-MM-DD');
       this.assertDateOrder(
         dto.transferDate,
         dto.newBillingStartDate || defaultBillingStart,
diff --git a/apps/server/src/rbac/rbac-presets.ts b/apps/server/src/rbac/rbac-presets.ts
index ea514f7..e4b0ac0 100644
--- a/apps/server/src/rbac/rbac-presets.ts
+++ b/apps/server/src/rbac/rbac-presets.ts
@@ -148,7 +148,7 @@ import dayjs from '../common/dayjs';
 
 export function getChinaDateParts(date = new Date()): { date: string; weekDay: number } {
   // Asia/Shanghai 无夏令时，固定 UTC+8 与 Intl en-CA 格式化等价
-  const c = dayjs.utc(date).add(8, 'hour');
+  const c = dayjs(date).utcOffset(8);
   const weekDay = c.day() === 0 ? 7 : c.day();
   return { date: c.format('YYYY-MM-DD'), weekDay };
 }
diff --git a/apps/server/src/sync/schedule-sync.helpers.ts b/apps/server/src/sync/schedule-sync.helpers.ts
index 559cbee..e634c8c 100644
--- a/apps/server/src/sync/schedule-sync.helpers.ts
+++ b/apps/server/src/sync/schedule-sync.helpers.ts
@@ -98,7 +98,7 @@ export function buildDailySchedulePlans(
   const toDate = new Date(`${syncTo}T00:00:00.000Z`);
 
   for (let date = new Date(fromDate); date <= toDate; date.setUTCDate(date.getUTCDate() + 1)) {
-    const dateStr = dayjs(date).utc().format('YYYY-MM-DD');
+    const dateStr = dayjs(date).utcOffset(8).format('YYYY-MM-DD');
     const weekDay = date.getUTCDay() === 0 ? 7 : date.getUTCDay();
 
     for (const schedule of schedules) {
diff --git a/apps/server/src/sync/sync.service.ts b/apps/server/src/sync/sync.service.ts
index e1bf143..7f609ba 100644
--- a/apps/server/src/sync/sync.service.ts
+++ b/apps/server/src/sync/sync.service.ts
@@ -71,8 +71,8 @@ export class SyncService {
       }
 
       const result = await this.attendanceImportService.importFromDingTalk({
-        startDate: dayjs(startDate).utc().format('YYYY-MM-DD'),
-        endDate: dayjs(endDate).utc().format('YYYY-MM-DD'),
+        startDate: dayjs(startDate).utcOffset(8).format('YYYY-MM-DD'),
+        endDate: dayjs(endDate).utcOffset(8).format('YYYY-MM-DD'),
         userIds,
         autoMatch: true,
       });