Abstract:To examine the ability of T213-SSI system on heavy rain forecasting, a nd to evaluate the application of satellite data on numerical prediction of heav y rain, this study used T213-SSI system to numerically simulate the heavy rai n fall in Sichuan Basin during July 16-19, 2007. This process was transition pr ocess of precipitation under adjusting of westerlies system and caused severe da mage. It is very difficult to be predicted and is very deserved to be researched . Three experiments are completed in this study using different data during diff erent period. The first experiment only uses conventional observations; the seco nd uses conventional observations and satellite microwave data during continuous 10 days. The last experiment uses conventional observation and satellite microw ave data during 6 hours. The results show that the second experiment is better t han the third. It means that satellite data need to be used for a long time to a chieve a good effect. In addition, employing of long time satellite data can imp rove large scale environmental flow. Thus, the heavy rain process will be close r to the truth. In the end, AMSU-A and AMSU-B data are very influential to the temperature and moisture fields respectively.