Abstract: In order to reduce the quality of the SCARA robot and improve the overall performance of the robot, a lightweight design idea of robot mechanics simulation analysis and topology optimization is proposed in this paper. The force on the arm of the robot under operating conditions is analyzed, and the statics analysis and mode analysis of the SCARA robotic large arm joints are conducted by using ABAQUS software. Then the topology optimization unit in ABAQUS is used to optimize the structure according to the analysis results. The analysis results show that the actual weight loss of the optimized boom is 1.189kg. Through the statics analysis and verification, it is found that the overall deformation is reduced by 21.1% and the low-order natural frequency is significantly increased. Through this optimization analysis, the purpose of reducing the boom weight and improving its structural performance is achieved.