Assuming the clearness and cloudless weather in Beijing area, the received solar radiation power is simulated according to three different auto-tracking solar systems and fixed solar system by Matlab. The tracking intervals of three different auto-tracking solar systems are separately 60mins, 30mins and 10mins. The daily mean solar radiation, the monthly mean solar radiation and the yearly mean solar radiation are simulated for three auto-tracking solar systems and fixed solar system. The simulation results can be used as the auto-tracking solar system design reference for engineers, and helpful for solar system optimizing.