Two-dimensional rough sea surface is generated based on JONSWAP sea spectrum, then the geometric optics approximation and Kirchhoff approximation are applied to calculate the light scattering. Each facet is treated as a surface with small roughness instead of a smooth plane, and the shadowing function for arbitrary incident and scattering angles is obtained with the projecting and ray tracing methods, hence making the results more accurate. Finally the image of sea surface is simulated in the 3 μm～5 μm band, which is of great reference value for reducing the interference to the sensor operating in the infrared by the scattering of sunshine from rough surface.