Abstract: Based on the Kelvin wake model by the point-source disturbance method, ship wakes at different speeds are simulated. In practical terms, the ship wake is not only affected by the parameters of ship, but also modulated by the wind-driven ocean waves. In order to build a better model, the ship wake in the rough sea surface is obtained by the linear summation of the rough sea surface produced by the Pierson-Moscowitz (PM) spectrum and the Kelvin wake. Utilizing the composite model, the variation of the single and bistatic radar cross sections (RCS) with scattering angles are investigated by the physical optics (PO) method. The simulation of the electromagnetic scattering of ship wake in rough sea surface is achieved. The realization of this process will be useful for a better simulation of the Kelvin wake in synthetic aperture radar(SAR) imaging, and provide a foundation for the recognition of vessel and its wakes.