diff --git a/src/db/database.ts b/src/db/database.ts
index 3f3e502..68c9a4c 100644
--- a/src/db/database.ts
+++ b/src/db/database.ts
@@ -1,4 +1,5 @@
 import Dexie, { type Table } from 'dexie';
+import type { TtsSettings } from '../types/settings';
 import type { Word, StudyProgress, StudyStats } from '../types/vocabulary';
 
 export interface WordEntry extends Word {
@@ -9,11 +10,32 @@ export interface ProgressEntry extends StudyProgress {
   syncedAt?: Date;
 }
 
+interface SettingsEntry {
+  key: string;
+  value: TtsSettings;
+}
+
+type ImportedWordEntry = Omit<Word, 'addedAt'> & {
+  addedAt?: Date | string;
+};
+
+interface ImportedProgressEntry extends Omit<StudyProgress, 'nextReviewDate' | 'lastStudiedDate'> {
+  nextReviewDate: Date | string;
+  lastStudiedDate: Date | string;
+  syncedAt?: Date | string;
+}
+
+interface BackupPayload {
+  words?: ImportedWordEntry[];
+  progress?: ImportedProgressEntry[];
+  stats?: StudyStats;
+}
+
 export class FrenchVocabDB extends Dexie {
   words!: Table<WordEntry>;
   progress!: Table<ProgressEntry>;
   stats!: Table<StudyStats & { id: string }>;
-  settings!: Table<{ key: string; value: any }>;
+  settings!: Table<SettingsEntry>;
 
   constructor() {
     super('FrenchVocabDB');
@@ -564,16 +586,36 @@ export async function exportData() {
 }
 
 // 导入数据
-export async function importData(data: any) {
-  if (data.words) {
+const normalizeWordEntry = (word: ImportedWordEntry): WordEntry => ({
+  ...word,
+  addedAt: word.addedAt ? new Date(word.addedAt) : new Date(),
+});
+
+const normalizeProgressEntry = (progress: ImportedProgressEntry): ProgressEntry => ({
+  ...progress,
+  nextReviewDate: new Date(progress.nextReviewDate),
+  lastStudiedDate: new Date(progress.lastStudiedDate),
+  syncedAt: progress.syncedAt ? new Date(progress.syncedAt) : undefined,
+});
+
+export async function importData(data: unknown) {
+  if (!data || typeof data !== 'object') {
+    throw new Error('Invalid backup data.');
+  }
+
+  const backup = data as BackupPayload;
+
+  if (Array.isArray(backup.words)) {
     await db.words.clear();
-    await db.words.bulkAdd(data.words);
+    await db.words.bulkAdd(backup.words.map(normalizeWordEntry));
   }
-  if (data.progress) {
+
+  if (Array.isArray(backup.progress)) {
     await db.progress.clear();
-    await db.progress.bulkAdd(data.progress);
+    await db.progress.bulkAdd(backup.progress.map(normalizeProgressEntry));
   }
-  if (data.stats) {
-    await db.stats.put({ ...data.stats, id: 'main' });
+
+  if (backup.stats) {
+    await db.stats.put({ ...backup.stats, id: 'main' });
   }
 }