Tropical cyclones Bilis and Kaemi have similar track and construction but their intensity of rainfall are very different. Their circulation and phy sical fields are compared and the conclusions show that the rainfall of landing tropical cycl ones is associated with the prevailing northeast air flow at upper level and i ntensified southwest monsoon. The low level convergence, high level divergence, ascending motion, water vapor transport and instability energy for these two tr opical cyclones over South China were significantly different under the differen t patterns, resulting in different rainstorms during the two tropical cyclones.