Abstract: Taking a stainless steel car body as the research object in this article,finite element simulation software was used to calculate the static strength of the car body. Based on the super-element method and the variable density method,the topology optimization on the 7 mm diameter welding spots of the side walls was carried out. Then the optimization result was improved manually. On the premise that the static strength met the relevant standards and technical conditions,977 redundant welding spots were removed. That accounted for 10.5% of the total number of welding spots on the side wall. The optimization process was efficient and the results were significant,which provided a beneficial reference for the layout design of solder joints in the future.