Combining simple genetic algorithms with simulated annealing,a new genetic simulated annealing algorithms is obtained with the characteristics of global searching and optimum. This method is used to fit experimental data to bidirectional reflectance distribution function(BRDF)statistical model in order to obtain more light scattering information of rough surface from satellite. And we also get the 3D BRDF distribution of the sample plane. The results are in accordance with experimental data.