The scattering prediction of 3D objects are often treated with EFE - MOM, where the basis function is one of the most important factors affecting the accuracy and efficiency of the method. Double liner quadrangles are used to model the surface of scattering object, a new kind of hybrid basis function based on this quadrangle is presented in this paper, and the RCS is calculated by using this method. The singular integral problems are found in this process, so the main work of this paper is to solve this singular problem. The final result indicates that the method used in this process is correct and efficient.