The variation of summer precipitation over Huanghuai region is very coordinate. Using SVD technique, the relationship between 100hPa geopotential height over the north Pacific and summer precipitation in the Huanghuai region is studied. The results show that the first mode derived from SVD indicates the key coupled characteristics of the geopotential height and the precipitation field with closely time-space correlation. In the severe summer drought/flood years, the height departure of 100hPa over the north Pacific(40～60°N,160°E～160°W) is remarkably positive/negative. It is the signal of prediction of summer precipitation in the Huanghuai region.