Abstract: Based on the study of SST charact eristics of North Pacific in pre-winter and spring of summer flood/drought in the middle and lower reaches of Yangtze River,the concept of SST strong signal which affects regional flood/drought is put forward.While choosing the SST key areas,the response of the general circulation in Northern Hemisphere to SST anomaly of equatorial Eastern Pacific is discussed further.The correlation between East Pacific SST and the seasonal height difference of North Hemisphere is studied also.It is shown that,the abnormal vertical motion in the equatorial Weste Pacific via Walker circulation may respond to SST anomaly in the equatorial Easte Pacific,and form the PNA-like Great Circle wave train.In addition,the wave train mani fests as systems related to subtropical high,westerly trough and blocking high,showing quasistat ionary merid ional w aves feature.This kind of wave train structure describes the teleresponse dynamic features of local flood/drought at mid and high latitudes to abnormal SST at lower latitude.