Abstract: EM scattering from sea surface can be described by the integral equation for dielectric (PMCHW). According to the characteristics of impedance matrix, mutualcoupling iteration and multilevel fast multipole algorithm (MLFMA) are introduced to solve the integral equation, so that the electric current and magnetic current are calculated. The microwave scattering on different kinds of sea surface situation has been simulated by this method, and the conclusion is compared with the related literatures, and the result shows the correctness of this meothd.