Abstract: In the 1950s and 1960s, summer rainfall was abundant over North China (NC) and below average over the middle and lower reaches of Yangtze River (YR). While in the 1980s and 1990s, North China was obsessed with severe droughts and YR was more flooded. In case of the opposite spatial distribution of summer rainfall over East China (ECSR) between the two periods, by wavelet analysis, ECSR from 1951 to 2004 have been studied and it was found that both summer rainfalls over NC and over YR exist obvious interdecadal variations with different time scales. For variations with time scales shorter than 24 years, morlet wavelet analysis shows that the phase between summer rainfall over NC and YR is not fixed. For variations with longer time scale, study on orthogonal wavelet analysis was conducted and the results are in agreement with the opposite spatial distribution between the two periods as mentioned in the beginning. It proves that ECSR has the characteristic of interdecadal variations with longer periods. And for this kind of variation, 17 years are chosen from the two periods and make a contrast of their SST distribution and atmospheric circulation. Results show that they are totally different in 1950s and 1960s from that in the 1970s and 1980s. Finally, by comparing SST distribution and atmospheric circulation in recent years with that in the previous years, the possible trend of ECSR in the future are discussed.