City of Yazd is located on the yellow radiation belt and has a high potential as regards receiving solar energy. Estimated radiated solar energy is about 7787 MJ/m2 per year. The object / purpose of this paper is to present two methods for estimating the total solar radiation on a plane surface and comparing this with pyranometric (pyrometric √ ) measurements data (in this city) and determining the statistical error in this city. In the first method by obtaining the parameters including temperature, precipitation, as well as sunshine and radiation hours, from Meteorological organization (IRIMO) for the duration of 1982 till 2003 the regression equation of Radiation versus these parameters was derived. In the second method (Angstrom Model) by using the data of pyranometric (pyrometric) and sunshine hours in the same time duration and calculating the rest of the parameters the amount of Radiation was estimated. From investigation by statistical software SPSS, it was observed that the statistical errors in the first method were higher, and that statistic correlation exists between the independent variables considered and also these parameters are interacted on each other, and that finally the only independent parameter is the sunshine hours. So for this purpose, when the amount of the radiation is not available, using the Angstrom equation “ 0.345 0.398( ) N n H H = + o ” is suggested for city of Yazd. 1)