Abstract: Using the brightness temperature (TB) data of TRMM Microwave Imager (TMI) from 2007 to 2009, we calculated the maximum,minimum, average values and the ratio of pixels over the threshold (AREA) in different regions of the TB and polarization correction temperature (PCT) from 9 channels (10, 19, 21, 37 and 85 GHz channel), and investigated the relationship between the TB and the Tropical Cyclone (TC) intensity. The results are as follows. The TC intensity may be well reflected by TB data, and the highest correlation coefficient can reach 0.83, and the linear fitting root mean square error is close to business error. TB from low frequency channels is better than that from high frequency channels to estimate the TC intensity on sea. The TB in the area from 0.5° to 1.5° latitude away from the TC center give higher correlation with TC intensity, and the correlation in circular area is better than that in the ring area. For TC on the sea, the minimum value of TB has the best correlation with the TC intensity. For the low frequency channels, except for 10 GHz, the TB threshold value from 260 K to 280 K gives higher correlation with the TC intensity.