Considering the influences of atmospheric refraction on the satellite laser ranging, an algorithm for calculating the optical path differences based on ray tracing is studied. Firstly, the annual mean atmospheric refractivity modulus height profiles of 46 typical regions in China are fitted by using meteorological sounding datum and high level model datum synthetically. Secondly, the results calculated by the Marini-Murray model and ray tracing which is based on the monthly average model and the annual mean model are compared and analyzed. Then, the national distribution of the optical path difference of satellite laser ranging is presented. Finally, the relations between the optical path difference with the height above sea level of ranging site and the elevation of satellite are numerically investigated.