An electromagnetic wave scattering model based on a hybrid SPM/MoM technique has been developed for the study of the EM wave interaction of a conducting object above a rough surface. In this hybrid technique, the Green's function and surface variables are expanded in terms of the surface height function on the mean surface, so that the integral equations based on the extinction theorem and boundary conditions can be decomposed into different orders. Each order represents the problem of EM wave scattering from an object on a flat interface excited by a wave from an equivalent source. With the introduction of the dyadic Green's function for layered media, the integral equations are reformulated and solved without involving the surface variables on the interface. Since the returned fields using the hybrid technique are expressed term by term, the EM wave interaction of the object with the rough surface can be clearly identified and characterized. The total returned fields calculated by the hybrid technique, which are the sum of individual interaction terms, are compared with simulation results computed with the standard MoM, and good agreement is obtained.