Abstract: Lightweight design of mechanical grippers can enhance the dynamic response speed, reduce energy consumption, and enhance the stability of the overall system. Based on the Mayfly algorithm, a method for lightweight designing of mechanical grippers is proposed in this paper. The principle of the proposed method and its application in lightweight design are discussed. To validate the effectiveness of this method, a three-finger gripper is lightweight designed by the proposed method. Through modeling and optimization analysis of a mechanical gripper, the effectiveness of the design method is verified. From the results, it can be found that the proposed method effectively reduces the gripper’s weight while maintaining its structural strength. The proposed method has important value and significance in reducing operating cost and improving operating efficiency of the mechanical gripper.