The atmospheric circulation anomalies of the continuous heavy rainfall over Yangtze-Huaihe river basin from May to July in 1991 were analyzed, moreover, the roles of water vapor transmission and cold air activities leading to this heavy rainfall were also compared. Results show that the deeper East Asia trough upon Northeast China and the unconspicuous block over the sea of Okhotsk led the cold air southward during the heavy rainfall. And the obviously westward subject position of the stronger western Pacific subtropical high over low-level areas was favorable for the northward movement of the warm and humid airflow from the West Pacific to the Yangtze-Huaihe river basins and the convergence with cold air in North China, which caused the prosperous precipitation. The definition of I_q and I_T found that the temperature and moisture had almost the equivalent effects in the lower troposphere.