In order to overcome the difficulties of ANSYS finite element analysis (FEA) on complicated and large-scale structures, the computer aided design (CAD) software UG and the FEA software ANSYS are combined together. The practical model, finite element model, material property, load and restricting condition are accomplished in UG software. Then the solving file is created and put into ANSYS software to operate. The results show that the use of the method presented in this paper brings into full play the merits of UG software in building models and the powerful superiority of ANSYS software in algorithms. The method makes full use of the modifiability of the solving file and the openness of the ANSYS software, which integrates the feasibility of analysis with the calculation precision to the utmost. Thus, the method proposed in this paper opens up a new way to FEA for complicated and large-scale structures.