Abstract: The relationships between the probable control factors, such as the sea surface temperature (SST) in the equatorial Eastern Pacific and the subtropical high etc., and drought/flood in the Changjiang valley are studied by using the related moment analysis. The contribution of each factor to the formation of drought/flood is also discussed. The results show that the abnormal change of all factors in the earlier stage has influence, to a different degree, on the variation of precipitation in summer. The relationship is shown principally by the abnormal drought/flood years. The correlation of the SST, SOI and subtropical high with the drought/flood is persistent to a certain degree. The synthetical analysis of the factors indicate that SST, SOI, subtropical high and the temperature in the Changjiang valley area have greater contribution to the formation of drought/flood.