Endactuator is very important for realizing fast, reliable and efficient transmission in substrate detection of semiconductor packaging. Under the condition of satisfying material strength and structure stiffness, a 3D model of the endactuator was established with the goal to reduce the weight of the endactuator. The static calculation and modal analysis of the endactuator of the substrate transfer robot were performed with ANSYS software. Then the stress, strain characteristics and corresponding modes of the endactuator under the maximum load were obtained. Based on the optimized topology, a new endactuator structure was established. And the strength of the new structure was checked, verifying the validity of the design scheme. The results demonstrate that the first four order natural frequencies of the endactuator are much higher than the gyrofrequency of the servomotor and the quality of the new structure is reduced by 26.7%. It achieves the goal of lightweight and provides a new technical solution for the subsequent development of related products.