Abstract: Based on the data of monthly mean SST of the North Pacific Ocean by National Climate Center during 1951—2002, the analytical methods of composite analysis and multi variable factors variance and also the method of correlation analysis for the relationship of the summer east China rainfall patterns and the SSTA of south and north in North Pacific Ocean are applied. It is found that the rainfall patterns have a close relation to the SSTA of North Pacific Ocean during the previous period from January to May. Though the distribution of rainfall patterns in rainy season is connected with different previous SSTA composite fields, there are only some key areas in the north and the south that can pass the significant test level in previous period, especially in preceding January. The key areas in north and south which have close negative correlation lie on the neighborhood of the extratropical Oyashio (40°—50°N, 160°E—180°), the West Wind Drift field (30°—40°N, 175°—145°W) and the middle part of The North Pacific Ocean in equator (10°S—0°, 175°—145°W) respectively. When the SST of key areas are regarded as the discrimination factors, the discrimination analysis of rainfall pattern shows that the discrimination accuracy of discriminating equation set up by regarding more key areas as discrimination factors is higher than the discriminating equation set up by regarding only one key area or the SST index defined by regarding the composite of some SST areas as discrimination factors. Those are the summer east China rainfall patterns which have a close connection with the synthetic effect of more SST areas. Further research on the correlation coefficients between eigenvalues of summer 500 hPa western Pacific subtropical high and the geopotential height of 500 hPa in the preceding January. and the SST index defined by discriminating equation in the preceding January. indicates that there are two possible ways of how the SST discriminating index affect the rainfall patterns of flood season in China. On one hand the atmospheric circulation anomaly is brought, especially the North Pacific Oscillation anomalies, and the PNA atmospheric teleconnection associate is given, then the summer east China precipitation is affected. On the other hand, it leads to the anomalies of eigenvalues of summer 500 hPa western Pacific subtropical high, especially the anomalies of the proportions, intension and westward ridge point of subtropical high. As a result the summer east China precipitation is affected. It is obvious that the SST anomalies in preceding January of the north and the south in North Pacific Ocean have a very close connection with the summer east China rainfall patterns, and it has important synoptic climatological significance.