diff --git a/src/app/service/content/gm_api/gm_api.ts b/src/app/service/content/gm_api/gm_api.ts
index 370e0dc8e..8c955decd 100644
--- a/src/app/service/content/gm_api/gm_api.ts
+++ b/src/app/service/content/gm_api/gm_api.ts
@@ -1278,7 +1278,19 @@ export default class GMApi extends GM_Base {
   @GMContext.API({})
   GM_setClipboard(data: string, info?: GMTypes.GMClipboardInfo, cb?: () => void) {
     if (this.isInvalidContext()) return;
-    this.sendMessage("GM_setClipboard", [data, info])
+    // 物件参数意义不明。日后再检视特殊处理
+    // 未支持 TM4.19+ application/octet-stream
+    // 参考： https://github.com/Tampermonkey/tampermonkey/issues/1250
+    let mimetype: string | undefined;
+    if (typeof info === "object" && info?.mimetype) {
+      mimetype = info.mimetype;
+    } else {
+      mimetype = (typeof info === "string" ? info : info?.type) || "text/plain";
+      if (mimetype === "text") mimetype = "text/plain";
+      else if (mimetype === "html") mimetype = "text/html";
+    }
+    data = `${data}`; // 强制 string type
+    this.sendMessage("GM_setClipboard", [data, mimetype])
       .then(() => {
         if (typeof cb === "function") {
           cb();
@@ -1294,7 +1306,11 @@ export default class GMApi extends GM_Base {
   @GMContext.API({ depend: ["GM_setClipboard"] })
   ["GM.setClipboard"](data: string, info?: string | { type?: string; mimetype?: string }): Promise<void> {
     if (this.isInvalidContext()) return new Promise<void>(() => {});
-    return this.sendMessage("GM_setClipboard", [data, info]);
+    return new Promise<void>((resolve) => {
+      this.GM_setClipboard(data, info, () => {
+        resolve();
+      });
+    });
   }
 
   @GMContext.API()
diff --git a/src/app/service/offscreen/gm_api.ts b/src/app/service/offscreen/gm_api.ts
index b9ea11e8a..87943cdc8 100644
--- a/src/app/service/offscreen/gm_api.ts
+++ b/src/app/service/offscreen/gm_api.ts
@@ -1,5 +1,6 @@
 import { BgGMXhr } from "@App/pkg/utils/xhr/bg_gm_xhr";
 import type { IGetSender, Group } from "@Packages/message/server";
+import { mightPrepareSetClipboard, setClipboard } from "../service_worker/clipboard";
 
 export default class GMApi {
   constructor(private group: Group) {}
@@ -11,32 +12,12 @@ export default class GMApi {
     bgGmXhr.do();
   }
 
-  textarea: HTMLTextAreaElement = document.createElement("textarea");
-
-  clipboardData: { type?: string; data: string } | undefined;
-
-  async setClipboard({ data, type }: { data: string; type: string }) {
-    this.clipboardData = {
-      type,
-      data,
-    };
-    this.textarea.focus();
-    document.execCommand("copy", false, <any>null);
+  async setClipboard({ data, mimetype }: { data: string; mimetype: string }) {
+    setClipboard(data, mimetype);
   }
 
   init() {
-    this.textarea.style.display = "none";
-    document.documentElement.appendChild(this.textarea);
-    document.addEventListener("copy", (e: ClipboardEvent) => {
-      if (!this.clipboardData || !e.clipboardData) {
-        return;
-      }
-      e.preventDefault();
-      const { type, data } = this.clipboardData;
-      e.clipboardData.setData(type || "text/plain", data);
-      this.clipboardData = undefined;
-    });
-
+    mightPrepareSetClipboard();
     this.group.on("xmlHttpRequest", this.xmlHttpRequest.bind(this));
     this.group.on("setClipboard", this.setClipboard.bind(this));
   }
diff --git a/src/app/service/service_worker/clipboard.ts b/src/app/service/service_worker/clipboard.ts
new file mode 100644
index 000000000..2948715bc
--- /dev/null
+++ b/src/app/service/service_worker/clipboard.ts
@@ -0,0 +1,39 @@
+let textareaDOM: HTMLTextAreaElement | undefined;
+let customClipboardData: { mimetype: string; data: string } | undefined;
+
+// 抽出成独立处理。日后有需要可以改成 chrome API
+export const setClipboard = (data: string, mimetype: string) => {
+  if (!textareaDOM) {
+    throw new Error("mightPrepareSetClipboard shall be called first.");
+  }
+  customClipboardData = {
+    mimetype,
+    data,
+  };
+  textareaDOM!.focus();
+  document.execCommand("copy", false, <any>null);
+};
+
+// 设置 setClipboard 相关DOM
+export const mightPrepareSetClipboard = () => {
+  if (textareaDOM) {
+    return;
+  }
+  if (typeof document !== "object") {
+    throw new Error(
+      "mightPrepareSetClipboard shall be only called in either Chrome offscreen or FF background script."
+    );
+  }
+  textareaDOM = document.createElement("textarea") as HTMLTextAreaElement;
+  textareaDOM.style.display = "none";
+  document.documentElement.appendChild(textareaDOM);
+  document.addEventListener("copy", (e: ClipboardEvent) => {
+    if (!customClipboardData || !e?.clipboardData?.setData) {
+      return;
+    }
+    e.preventDefault();
+    const { mimetype, data } = customClipboardData;
+    customClipboardData = undefined;
+    e.clipboardData.setData(mimetype || "text/plain", data);
+  });
+};
diff --git a/src/app/service/service_worker/gm_api/gm_api.ts b/src/app/service/service_worker/gm_api/gm_api.ts
index 1e85ee677..e59400566 100644
--- a/src/app/service/service_worker/gm_api/gm_api.ts
+++ b/src/app/service/service_worker/gm_api/gm_api.ts
@@ -42,6 +42,7 @@ import {
 } from "./gm_xhr";
 import { headerModifierMap, headersReceivedMap } from "./gm_xhr";
 import { BgGMXhr } from "@App/pkg/utils/xhr/bg_gm_xhr";
+import { mightPrepareSetClipboard, setClipboard } from "../clipboard";
 
 let generatedUniqueMarkerIDs = "";
 let generatedUniqueMarkerIDWhen = "";
@@ -1246,10 +1247,15 @@ export default class GMApi {
   }
 
   @PermissionVerify.API()
-  async GM_setClipboard(request: GMApiRequest<[string, GMTypes.GMClipboardInfo?]>, _sender: IGetSender) {
-    const [data, type] = request.params;
-    const clipboardType = type || "text/plain";
-    await sendMessage(this.msgSender, "offscreen/gmApi/setClipboard", { data, type: clipboardType });
+  async GM_setClipboard(request: GMApiRequest<[string, string]>, _sender: IGetSender) {
+    const [data, mimetype] = request.params;
+    if (typeof document === "object" && document?.documentElement) {
+      // FF background script
+      mightPrepareSetClipboard();
+      setClipboard(data, mimetype);
+    } else {
+      await sendMessage(this.msgSender, "offscreen/gmApi/setClipboard", { data, mimetype });
+    }
   }
 
   @PermissionVerify.API()