diff --git a/api/@internal/component/ets/common.d.ts b/api/@internal/component/ets/common.d.ts
index d410c9d35a5e2e7a03c9743edc7914167f3059b2..5c1fc59a44facda33366523a0e27e5db3e98d658 100644
--- a/api/@internal/component/ets/common.d.ts
+++ b/api/@internal/component/ets/common.d.ts
@@ -227,7 +227,7 @@ declare interface AnimateParam {
    * Animation curve.
    * @since 7
    */
-  curve?: Curve | string;
+  curve?: Curve | string | ICurve;
   /**
    * Animation playback mode. By default, the animation is played from the beginning after the playback is complete.
    * @since 7
@@ -250,6 +250,18 @@ declare interface AnimateParam {
   onFinish?: () => void;
 }
 
+/**
+ * Interface for curve object.
+ * @since 9
+ */
+interface ICurve {
+  /**
+   * Get curve value by fraction.
+   * @since 9
+   */ 
+  interpolate(fraction : number) : number;
+}
+
 /**
  * Defines the motion path options.
  * @since 7
diff --git a/api/@ohos.curves.d.ts b/api/@ohos.curves.d.ts
index e3a377d6cea5acb289960fa17e9223cf55a1d2f8..68cd78e3beba6d6494148c74bf1cefcaafe0db08 100644
--- a/api/@ohos.curves.d.ts
+++ b/api/@ohos.curves.d.ts
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2021 Huawei Device Co., Ltd.
+* Copyright (c) 2021-2022 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
@@ -40,29 +40,70 @@ declare namespace curves {
     Friction,
   }
 
+  /**
+   * Interface for curve object.
+   * @since 9
+   */
+  interface ICurve {
+   /**
+   * Get curve value by fraction.
+   * @since 9
+   */ 
+    interpolate(fraction : number) : number;
+  }
+
+  /**
+   * Initializes the interpolator curve when called.
+   * @since 9
+   */
+  function init(curve?: Curve): ICurve;
+
   /**
    * Initializes the interpolator curve when called.
    * @since 7
+   * @deprecated since 9
    */
   function init(curve?: Curve): string;
 
+  /**
+   * Constructs a step curve when called.
+   * @since 9
+   */
+  function steps(count: number, end: boolean): ICurve;
+
   /**
    * Constructs a step curve when called.
    * @since 7
+   * @deprecated since 9
    */
   function steps(count: number, end: boolean): string;
 
+  /**
+   * Constructs a third-order Bezier curve when called.
+   * @since 9
+   */
+  function cubicBezier(x1: number, y1: number, x2: number, y2: number): ICurve;
+
   /**
    * Constructs a third-order Bezier curve when called.
    * @since 7
+   * @deprecated since 9
    */
   function cubicBezier(x1: number, y1: number, x2: number, y2: number): string;
 
+  /**
+   * Constructs a spring curve when called.
+   * @since 9
+   */
+  function spring(velocity: number, mass: number, stiffness: number, damping: number): ICurve;
+
   /**
    * Constructs a spring curve when called.
    * @since 7
+   * @deprecated since 9
    */
   function spring(velocity: number, mass: number, stiffness: number, damping: number): string;
+
 }
 
 export default curves;