The Joint North Sea Wave Project(JONSWAP) spectrum sea surface is mainly determined by parameters such as wind speed, wind area and spectral peak factor. The double stacking method is utilized to generate three-dimensional JONSWAP sea surface. The influence of direction concentration and spectral peak factor on the surface geometry model is analyzed. The physical optics method is adopted to analyze the changes of average backward scattering coefficient of JONSWAP spectrum sea surface with the direction concentration and the spectral factor. The simulation results show that the influence of spectral factor on the average backward scattering coefficient of the surface is less than 1 dB, and the influence of direction concentration parameters on the average backward scattering coefficient of the surface is more than 5 dB. Therefore, when studying the electromagnetic scattering of the JONSWAP spectral sea surface, the spectral peak factor can take the mean value, and the direction concentration parameter should be determined according to the wave growth state.