In order to solve the problem that the heavy weight blanks are difficult to transfor in each process of automatic forging production, the mechanical structure and driving system of the gripper arm for manipulator were designed to achieve the high load ratio. Then, 3D modeling of  manipulator equipment was carried out by SolidWorks, and the calculation of related parameters for power source, linear guideway and other mechanisms was realized. Furthermore, the static analysis and structural optimization on the gripper arm were carried out, and the gripping performance of  manipulator was verified by the robot load simulation platform. In order to meet the economy of product and the convenience of manufacturing, the gripper arm applied the strategy of modular design, the main body was made of standard I-beam steel, the clamping and fixing ends were fixed by welding modules, and the overall structure was designed to be lightweight. The results show that the weight of the gripper arm for manipulator is 75 kg after lightweight, and when using the KUKA KR210 robot with higher economic benefits, the maximum load is 70 kg. The load ratio of the gripper arm reaches 1∶1.1, which meets the design requirements. Thus, its high load ratio is beneficial to the high-quality production of heavy weight components.