Abstract: A method of CAD CAE integration based on the interface of STL is presented in the paper. It bridges the gap between most CAD systems and CAE systems. By the method, STL data is analyzed, checked and verified first. Then 3D tetrahedron mesh is generated automatically based on the corrected and combined STL data. The data file of finite element mesh can be input to most CAE systems for calculation and analysis. Examples show that the method is simple, useful and effective.