Estimation of the rainfall in the ungauged areas is very difficult. Remote is an important approach for resolving this problem in re - cent years. The applicability of TRMM precipitation data in Tianshan Mountains was studied in this paper. By comparing the TRMM data with observed data of the 21 meteorology stations from 2000 to 2010, we found there was a good consistency between them in different time scales and spatial scales. The results show that the correlation coefficient (R2) is greater than 0.7 in different temporal scales. The relative errors are between -40% and 40% in different spatial scales. It also indicates that the TRMM data could be used in the study area. This analysis is mean - ingful for the water resource study in ungauged areas.