The work aims to improve the strength and weight, etc. of the studied industrial mechanical parts through such two main methods as finite element analysis and optimal design used to design modern mechanical components and parts. By building the 3D model of rotary joint fixed support for robot based on 3D software and carrying out dynamic simulation with ADAMS simulation software, the stress analysis of the support under the condition of the rotary joint was obtained. Then stress analysis and optimal design were conducted in the Ansys Workbench according to the data results analyzed. The weight of the fixed support decreased by 21.7%, and the overall strength was enhanced. The optimization method works well and it can significantly improve the weight and strength of the structures of mechanical components and parts.