Abstract: From 1983 to 1984, 14 solar radiation observation stations which are located in different parts of our country and with different climate features were chosen for the simultaneous observation of natural illumination with solar radiation hourly every day. In this paper, according to the data the light equivalent of total solar radiation has been given. A multivariate regression equation to calaulate the annual and monthly mean values of the light equivalent of total solar radiation at 14 observation stations is formed.The variables of the equation include latitude, elevation,mean absolute humidity on the surface and the hours of sunshine.The result of the equation shows that the relative error is less than 10 percent.The light equivalents of total solar radiation for 464 observation stations were calculated by means of the multivariate regression equations which were obtained upon the data of 14 observation stations. The total illumination is given by the light equivalent of total radiation multiplying the total radiation.The climate values of total illumination for each station are also calculated according to its light equivalent of total radiation and total solar radiation value. Finally, the climate charts of total illumination for our country have been drawn.