In order to solve the unreasonable RS232 shell structure design, the topology of RS232 serial port shell structure based on nonlinear mechanics is optimized and analyzed. According to the combination relation of the interface shell structure, the six-parameter Iwan model of the non-uniform density function is constructed. At the same time, the mathematical model of topological optimization is used to delete and judge isotropic materials and a progressive structural optimization method is obtained by nonlinear finite element analysis. The results show that the method can realize the reasonable distribution of materials and optimize the use of materials.