In order to improve the quality and efficiency of the complex product structure design, research the multi finite element analysis method and analysis process of ANSYS mechanical structure, put forward a fast finite element analysis method. Taking UG/NX and ANSYS as platform, developed fast finite element analysis program, inputted analysis parameter in UG interface and chose related geometry element, the program automatically used ANSYS analysis. Took stress joint analysis, bomb contact analysis and sensor cover modal analysis as example to verify. The verification results show that the program realizes the geometry element recognition from UG model to ANSYS finite element model. Automatically realize multi finite element analysis processes. It can simplify finite element analysis check process and complex operation, and improve the design efficiency.