Based on the NCEP reanalysis data and T213 data, the two typical heavy rainfall which occured in Sichuan and Chongqing in summer,2006 was analyzed. Th e result shows that the variation of 500hpa circulation, and the intrusion of co ld advection at upper air and the cold air at low level are favorable to the occ urrence of the heavy rainfall. On the other hand, the strengthen of the low leve l jet, wind speed pulsation are key to the heavy rainfall. The intensity and loc ation of the heavy rainfall are related to the convergence of water vapour in 85 0hpa, divergence at high level and the strengthen of the ascending motion。