The 12 uniform distributed meteorological stations in Yunnan can be used to carried out correlation analysis to precipitation data of TRMM 3B43 V7 products. Then the precipitation Z index was used for the evaluation of dry monitoring accurancy. The paper also analyzed the monthly drought temporary and spatial feature of great drought instance in Yunnan for 15 years. The results show that TRMM data have high precision and correlation coefficient (R2) in most of the stations is more than 0.9, majority of TRMM data are smaller than observed data. Annual rainfall in Yunnan has a decrease trend, the rainy season is mainly concentrated from May to October which accounts for 85.47% of annual precipitation. The precipitation gradually increases from northeast to southwest. The TRMM-Z indexes in single station and the whole province's stations are consistent with the actual drought trend. The correlation coefficient R2 of Z index in 11 stations are about 0.7~0.8, while the province's annual scale TRMM-Z index has higher precision than that of single station. Meanwhile, the drought monitoring instances monitored by TRMM-Z index is basically consistent with the observed temporal and spatial- distribution features and drought disaster is lower than the actual degree. So the monitoring method is practical in the area.