Abstract: In order to quickly calculate the composite electromagnetic scattering of the object above sea surface, the E-PILE+SMFIA/CAG is present in this paper, which combines the sparse-matrix flat-surface iterative approach-canonical grid (SMFSIA/CAG) method for sea surface and the method of moment (MoM) based on Rao-Wilton-Glisson (RWG) function for object.The tapered incident wave is chosen to reduce the truncation error.The Pierson-Moskowitz (PM) random sea surface is generated by using Monte-Carlo method.The composite bistatic scattering coefficients (BSC) of regular objects above sea surface are calculated by using introduced method.The validity of this method is verified by comparing the results with that of exist method.The BSC from a missile target above sea surface is calculated finally, and the dependences of bistatic scattering pattern upon the wind speed and the height of target is discussed.