Abstract: By using the correlation analysis between the Meiyu onset date (MOD) of the Yangtze-Huaihe River valley and SST, and composite analysis of general circulation in years of anomalous SST, the affection of SST to MOD is studied. The results show that the SSTA of Pacific, Indian Ocean and Atlantic can affect the MOD. When the SST of warm pool of western Pacific is high (low) from last Nov. to Jan., the MOD is early (late). The MOD is late when the SST of middle Pacific is high from Feb. to May. From May to June, the SST near Mascarene high has good indication to MOD, that is early (late) when the SST is high (low). From Feb. to May, the SST near the warm pool of western Pacific has good indication to MOD. In June, the SST to the east of Taiwan and southern Atlantic has affection to MOD.