In order to achieve the radiative forcing caused by the change of carbon dioxide concentration,a simplified net radiation flux model of the atmosphere was established.Based on the radiative transfer equation,the model can calculate the radiative forcing and net radiation flux at each layer of the atmosphere caused by the change of concentration of carbon dioxide.Compared with the RRTM-LW long wave radiative transfer model developed by the American center for atmospheric and environmental research,under the same conditions the error is less than 1%.