In order to represent optical scattering properties of the complex painted surfaces, based on microfacet theory for polarized bidirectional reflectance distribution function (BRDF), genetic algorithm is used to get the key parameters in the model. Numerical simulation is done using C++ language and the impact of the model parameters is analyzed. The comparison between numerical simulation results and experimental data indicate: this model has the higher precision for simulation, and can be used as a reference for target feature extraction and recognition in the future.