Abstract: The capacity of Tropical Rainfall Measuring Mission (TRMM) Satellite for measuring rainfall was examined by using TMI-85.5 GHz microwave image data and precipitation data during the heavy rainfall experiment in Southern China. As compared with the distribution of rain amounts in an hour with T_BB of 85.5 GHz microwave,it is clear that the center of heavy rain corresponds with an area of low T_BB value. The location and shape of T_BB distribution is similar to that of precipitation,and the larger rainfall rates,the lower T_BB. The statistic analysis shows that the correlation coefficients between T_BB and rain rates is negative and significant. Expecially,when the rain rate is over 7 mm/h,the correlation degree between T_BB and rain rate is more significaut. The results shows that TRMM/TMI-85.5 G has great ability to measure convective heavy rain.