Abstract: This paper takes the piston of an air compressor as the research object. Firstly, the finite element simulation analysis is carried out by using UGNX software to check whether its strength and displacement meet the safety requirements under working load （to clarify the optimization range）. Secondly, based on the simulation results and the topological optimization theory, with a full material cylinder of Ø42 mm*45 mm as the optimization space and the maximization of stiffness as the objective, fixed constraints are applied to the bottom surface of the piston and working load is applied to the top surface. The structural linear static topological optimization is carried out with the mass upper limit of 0.1 kg and 0.06 kg respectively. The optimization results show that the piston with a mass of 0.06 kg still meets the strength and displacement requirements, and the weight is reduced by 41.5% compared with the initial piston structure. This research optimizes the mechanical structure of the piston and provides methods and theoretical references for the lightweight design of the piston.