diff --git a/addon/chrome/content/syncList.xul b/addon/chrome/content/syncList.xul
index 64e725d..783b63e 100644
--- a/addon/chrome/content/syncList.xul
+++ b/addon/chrome/content/syncList.xul
@@ -40,6 +40,7 @@
         </listbox>
         <hbox flex="0">
             <button id="doupdate" label="&zotero.__addonRef__.syncList.doupdate.label;" oncommand="Zotero.Knowledge4Zotero.syncList.doUpdate();"></button>
+            <button id="changesyncperiod" label="&zotero.__addonRef__.syncList.changesyncperiod.label;" oncommand="Zotero.Knowledge4Zotero.syncList.changeSyncPeriod();"></button>
             <button id="dosync" label="&zotero.__addonRef__.syncList.dosync.label;" oncommand="Zotero.Knowledge4Zotero.syncList.doSync();"></button>
             <button id="changesync" label="&zotero.__addonRef__.syncList.changesync.label;" oncommand="Zotero.Knowledge4Zotero.syncList.changeSync();"></button>
             <button id="removesync" label="&zotero.__addonRef__.syncList.removesync.label;" oncommand="Zotero.Knowledge4Zotero.syncList.removeSync();"></button>
diff --git a/addon/chrome/locale/en-US/overlay.dtd b/addon/chrome/locale/en-US/overlay.dtd
index 2dcd49f..51c3ef0 100644
--- a/addon/chrome/locale/en-US/overlay.dtd
+++ b/addon/chrome/locale/en-US/overlay.dtd
@@ -54,6 +54,7 @@
 <!ENTITY zotero.__addonRef__.syncList.syncpath.label "Sync To">
 <!ENTITY zotero.__addonRef__.syncList.lastsync.label "Last Sync">
 <!ENTITY zotero.__addonRef__.syncList.doupdate.label "Refresh">
+<!ENTITY zotero.__addonRef__.syncList.changesyncperiod.label "Sync Period:">
 <!ENTITY zotero.__addonRef__.syncList.dosync.label "Sync">
 <!ENTITY zotero.__addonRef__.syncList.changesync.label "Change Folder">
 <!ENTITY zotero.__addonRef__.syncList.removesync.label "Remove This">
diff --git a/addon/chrome/locale/zh-CN/overlay.dtd b/addon/chrome/locale/zh-CN/overlay.dtd
index 9958c77..71c4a00 100644
--- a/addon/chrome/locale/zh-CN/overlay.dtd
+++ b/addon/chrome/locale/zh-CN/overlay.dtd
@@ -54,6 +54,7 @@
 <!ENTITY zotero.__addonRef__.syncList.syncpath.label "同步到">
 <!ENTITY zotero.__addonRef__.syncList.lastsync.label "最近同步">
 <!ENTITY zotero.__addonRef__.syncList.doupdate.label "刷新">
+<!ENTITY zotero.__addonRef__.syncList.changesyncperiod.label "同步周期:">
 <!ENTITY zotero.__addonRef__.syncList.dosync.label "同步">
 <!ENTITY zotero.__addonRef__.syncList.changesync.label "修改路径">
 <!ENTITY zotero.__addonRef__.syncList.removesync.label "取消同步">
diff --git a/src/events.ts b/src/events.ts
index 7446c94..ed335ee 100644
--- a/src/events.ts
+++ b/src/events.ts
@@ -1586,6 +1586,13 @@ class AddonEvents extends AddonBase {
     this._Addon.template.getCitationStyle();
     // Initialize sync notes
     this._Addon.sync.getSyncNoteIds();
+    // Initialize sync period
+    // Default sync period is 10s
+    if (
+      typeof Zotero.Prefs.get("Knowledge4Zotero.syncPeriod") === "undefined"
+    ) {
+      this._Addon.syncList.changeSyncPeriod(10);
+    }
   }
 }
 
diff --git a/src/sync.ts b/src/sync.ts
index c082b3a..839e853 100644
--- a/src/sync.ts
+++ b/src/sync.ts
@@ -193,7 +193,7 @@ class AddonSync extends AddonBase {
       noteItem.removeTag(sycnTag.tag);
     }
     noteItem.addTag(
-      `sync://note/?version=${noteItem._version}&path=${
+      `sync://note/?version=${noteItem._version + 1}&path=${
         path ? encodeURIComponent(path) : syncInfo["path"]
       }&filename=${
         filename ? encodeURIComponent(filename) : syncInfo["filename"]
@@ -206,11 +206,14 @@ class AddonSync extends AddonBase {
   setSync() {
     const _t = new Date().getTime();
     this.triggerTime = _t;
-    setTimeout(() => {
-      if (this.triggerTime === _t) {
-        this.doSync();
-      }
-    }, 10000);
+    const syncPeriod = Number(Zotero.Prefs.get("Knowledge4Zotero.syncPeriod"));
+    if (syncPeriod > 0) {
+      setTimeout(() => {
+        if (this.triggerTime === _t) {
+          this.doSync();
+        }
+      }, syncPeriod);
+    }
   }
 
   async doSync(
@@ -229,7 +232,7 @@ class AddonSync extends AddonBase {
       const filepath = decodeURIComponent(syncInfo.path);
       const filename = decodeURIComponent(syncInfo.filename);
       if (
-        Number(syncInfo.version) < item._version - 1 ||
+        Number(syncInfo.version) < item._version ||
         !(await OS.File.exists(`${filepath}/${filename}`)) ||
         forceNoteIds.includes(item.id)
       ) {
diff --git a/src/syncList.ts b/src/syncList.ts
index b8fa2d8..c2e90e0 100644
--- a/src/syncList.ts
+++ b/src/syncList.ts
@@ -14,7 +14,7 @@ class AddonSyncList extends AddonBase {
       window.open(
         "chrome://Knowledge4Zotero/content/syncList.xul",
         "",
-        "chrome,centerscreen,resizable,status,width=500,height=400"
+        "chrome,centerscreen,resizable,status,width=600,height=400"
       );
     }
   }
@@ -25,6 +25,9 @@ class AddonSyncList extends AddonBase {
   }
 
   doUpdate() {
+    if (!this._window || this._window.closed) {
+      return;
+    }
     const notes = Zotero.Items.get(this._Addon.sync.getSyncNoteIds());
     const listbox = this._window.document.getElementById("sync-list");
     let e,
@@ -77,6 +80,19 @@ class AddonSyncList extends AddonBase {
       });
       listbox.append(listitem);
     }
+
+    const periodButton = this._window.document.getElementById(
+      "changesyncperiod"
+    ) as XUL.Button;
+    const period =
+      Number(Zotero.Prefs.get("Knowledge4Zotero.syncPeriod")) / 1000;
+    periodButton.setAttribute(
+      "label",
+      periodButton.getAttribute("label").split(":")[0] +
+        ":" +
+        (period > 0 ? period + "s" : "disabled")
+    );
+    this._window.focus();
   }
 
   getSelectedItems(): ZoteroItem[] {
@@ -112,6 +128,22 @@ class AddonSyncList extends AddonBase {
     this.doUpdate();
   }
 
+  changeSyncPeriod(period: number = -1) {
+    if (period < 0) {
+      const inputPeriod = prompt("Enter synchronization period in seconds:");
+      if (inputPeriod) {
+        period = Number(inputPeriod);
+      } else {
+        return;
+      }
+    }
+    if (period < 0) {
+      period = 0;
+    }
+    Zotero.Prefs.set("Knowledge4Zotero.syncPeriod", Math.round(period) * 1000);
+    this.doUpdate();
+  }
+
   async removeSync() {
     let selectedItems = this.getSelectedItems();
     if (selectedItems.length === 0) {