diff --git a/aio/content/translations/cn/api-plan.md b/aio/content/translations/cn/api-plan.md
index 63dcbb3848..d72e79bcab 100644
--- a/aio/content/translations/cn/api-plan.md
+++ b/aio/content/translations/cn/api-plan.md
@@ -56,7 +56,7 @@
 [x]  | forms/FormControlName  | 0.34
 [x]  | core/Output  | 0.33
 [x]  | common/http/HttpInterceptor  | 0.30
-[ ]  | common/http/HttpRequest  | 0.29
+[x]  | common/http/HttpRequest  | 0.29
 [ ]  | router/CanActivate  | 0.27
 [ ]  | router  | 0.26
 [ ]  | animations/style  | 0.25
diff --git a/packages/common/http/src/request.ts b/packages/common/http/src/request.ts
index 30413cb8da..5e6b529875 100644
--- a/packages/common/http/src/request.ts
+++ b/packages/common/http/src/request.ts
@@ -12,7 +12,11 @@ import {HttpParams} from './params';
 /**
  * Construction interface for `HttpRequest`s.
  *
+ * `HttpRequest` 的构造接口。
+ *
  * All values are optional and will override default values if provided.
+ *
+ * 所有值都是可选的，如果提供了，则会覆盖默认值。
  */
 interface HttpRequestInit {
   headers?: HttpHeaders;
@@ -24,6 +28,8 @@ interface HttpRequestInit {
 
 /**
  * Determine whether the given HTTP method may include a body.
+ *
+ * 决定 `body` 中将包含哪种 HTTP 方法。
  */
 function mightHaveBody(method: string): boolean {
   switch (method) {
@@ -41,7 +47,11 @@ function mightHaveBody(method: string): boolean {
 /**
  * Safely assert whether the given value is an ArrayBuffer.
  *
+ * 安全地断言指定值是否 `ArrayBuffer`。
+ *
  * In some execution environments ArrayBuffer is not defined.
+ *
+ * 在某些运行环境中可能没有定义 `ArrayBuffer`。
  */
 function isArrayBuffer(value: any): value is ArrayBuffer {
   return typeof ArrayBuffer !== 'undefined' && value instanceof ArrayBuffer;
@@ -50,7 +60,11 @@ function isArrayBuffer(value: any): value is ArrayBuffer {
 /**
  * Safely assert whether the given value is a Blob.
  *
+ * 安全地断言指定值是否 `Blob`。
+ *
  * In some execution environments Blob is not defined.
+ *
+ * 在某些运行环境下可能没有定义 `Blob`。
  */
 function isBlob(value: any): value is Blob {
   return typeof Blob !== 'undefined' && value instanceof Blob;
@@ -59,7 +73,11 @@ function isBlob(value: any): value is Blob {
 /**
  * Safely assert whether the given value is a FormData instance.
  *
+ * 安全的断言指定的值是否为 `FormData` 实例。
+ *
  * In some execution environments FormData is not defined.
+ *
+ * 在某些运行环境下可能没有定义 `FormData`。
  */
 function isFormData(value: any): value is FormData {
   return typeof FormData !== 'undefined' && value instanceof FormData;
@@ -68,25 +86,37 @@ function isFormData(value: any): value is FormData {
 /**
  * An outgoing HTTP request with an optional typed body.
  *
+ * 一个外发的 HTTP 请求，带有一个可选的类型化的请求体（`body`）。
+ *
  * `HttpRequest` represents an outgoing request, including URL, method,
  * headers, body, and other request configuration options. Instances should be
  * assumed to be immutable. To modify a `HttpRequest`, the `clone`
  * method should be used.
  *
+ * `HttpRequest` 表示一个外发请求，包括 URL、方法、请求头、请求体和其它请求配置项。
+ * 它的实例都是不可变的。要修改 `HttpRequest`，应该使用 `clone` 方法。
  *
  */
 export class HttpRequest<T> {
   /**
    * The request body, or `null` if one isn't set.
    *
+   * 请求体，如果没有则为 `null`。
+   *
    * Bodies are not enforced to be immutable, as they can include a reference to any
    * user-defined data type. However, interceptors should take care to preserve
    * idempotence by treating them as such.
+   *
+   * 请求体无法确保自己是不可变的，因为它们可以包含指向任何自定义数据类型的引用。
+   * 不过，在拦截器中，要小心维护其幂等性 —— 把它们当做不可变对象。
    */
   readonly body: T|null = null;
 
   /**
    * Outgoing headers for this request.
+   *
+   * 本请求的外发请求头。
+   *
    */
   // TODO(issue/24571): remove '!'.
   readonly headers !: HttpHeaders;
@@ -94,37 +124,53 @@ export class HttpRequest<T> {
   /**
    * Whether this request should be made in a way that exposes progress events.
    *
+   * 该请求是否应该暴露出进度事件。
+   *
    * Progress events are expensive (change detection runs on each event) and so
    * they should only be requested if the consumer intends to monitor them.
+   *
+   * 进度事件很昂贵（在每个事件中都会执行一次变更检测），所以只有当消费者关心这些事件时才应该请求这些进度事件。
    */
   readonly reportProgress: boolean = false;
 
   /**
    * Whether this request should be sent with outgoing credentials (cookies).
+   *
+   * 此请求是否应该带着凭证（Cookie）一起外发。
    */
   readonly withCredentials: boolean = false;
 
   /**
    * The expected response type of the server.
    *
+   * 所期待的服务器响应类型。
+   *
    * This is used to parse the response appropriately before returning it to
    * the requestee.
+   *
+   * 它用来在把响应对象返回给被请求者之前以恰当的方式解析它。
    */
   readonly responseType: 'arraybuffer'|'blob'|'json'|'text' = 'json';
 
   /**
    * The outgoing HTTP request method.
+   *
+   * 外发 HTTP 请求的方法。
    */
   readonly method: string;
 
   /**
    * Outgoing URL parameters.
+   *
+   * 外发的 URL 参数。
    */
   // TODO(issue/24571): remove '!'.
   readonly params !: HttpParams;
 
   /**
    * The outgoing URL with all URL parameters set.
+   *
+   * 外发的 URL，及其所有 URL 参数。
    */
   readonly urlWithParams: string;
 
@@ -235,6 +281,8 @@ export class HttpRequest<T> {
   /**
    * Transform the free-form body into a serialized format suitable for
    * transmission to the server.
+   *
+   * 把无格式的请求体转换成适合传给服务器的序列化格式。
    */
   serializeBody(): ArrayBuffer|Blob|FormData|string|null {
     // If no body is present, no need to serialize it.
@@ -264,7 +312,11 @@ export class HttpRequest<T> {
    * Examine the body and attempt to infer an appropriate MIME type
    * for it.
    *
+   * 检测请求体，并尝试给它推断出一个合适的 MIME 类型。
+   *
    * If no such type can be inferred, this method will return `null`.
+   *
+   * 如果没有合适的 MIME 类型，该方法就会返回 `null`。
    */
   detectContentTypeHeader(): string|null {
     // An empty body has no content type.