A simple thermal model is developed for solar chimney thermal power system and validated by the comparison between the simulated results and those simulated by Schlaich et al. Based on a proposed 200 MW power plant in a desert in western China a special climate, which is formed around the giant solar chimney power plant by the volume of warm air flowing from the chimney outlet to a high altitude, is simulated and analyzed. An atmospheric circulation and rainfall are formed. It is found that the solar chimney power plant increases the chance of rainfall, especially for low-humidity air in the desert region, supporting the agriculture in the local area and promoting a part of the desert region to be reformed to fertile soil. Further, the effects of many factors on the rainfall area around a commercial solar chimney thermal power plant are also analyzed. It is concluded that by keeping other conditions equal, solar radiation of more than 706 W / m(2), a collector area of more than 10.45 km(2), a chimney height of less than 1250 m, a horizontal wind velocity of less than 15 m/s, and an ideal relative humidity from 23.5 to 30% are, respectively, chosen for rainfalls around the collector area.