diff --git a/api/@ohos.util.d.ts b/api/@ohos.util.d.ts
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+/*
+* Copyright (c) 2021 Huawei Device Co., Ltd.
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+* http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+declare namespace util {
+
+    /**
+     *  encoding name: support full encoding in ICU data utf-8 utf-16 iso8859 must support in all device
+     */
+    class TextDecoder {
+        /** the source encoding's name, lowercased. */
+        readonly encoding: string;
+        /** Returns `true` if error mode is "fatal", and `false` otherwise. */
+        readonly fatal: boolean;
+        /** Returns `true` if ignore BOM flag is set, and `false` otherwise. */
+        readonly ignoreBOM = false;
+        constructor(
+            encoding?: string,
+            options?: { fatal?: boolean; ignoreBOM?: boolean },
+        );
+        /** Returns the result of running encoding's decoder. */
+        decode(input?: ArrayBuffer | ArrayBufferView, options?: { stream?: false }): string;
+    }
+
+    /**
+     * TextEncoder takes a stream of code points as input and emits a stream of UTF-8 bytes.
+     */
+    class TextEncoder {
+        readonly encoding = "utf-8";
+
+        constructor();
+
+        /** Returns the result of encoder. */
+        encode(input?: string): Uint8Array;
+
+        /** encode string, write the result to dest array */
+        encodeInto(
+            input: string,
+            dest: Uint8Array,
+        ): { read: number; written: number };
+    }
+}
+
+export default util;
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