Abstract:In terms of NCEP/NCAR reanalysis data, HadISST1 dataset and several representative monsoon indices, the interdecadal variation of the relationship between ENSO-related EAWM and the following East Asian summer monsoon (EASM) was investigated by the methods of regression and moving-correlation. Moreover, the reasons of the variation were also analyzed. Results show that the negative relationship is weak during 1965-1979,but became strong and statistically significant during 1980-2004. A strong ENSO-related EAWM led to negative geopotential height anomalies in middle-level and lower-level anomalous cyclonic circulation over the western North Pacific, which persisted from winter to summer and weakened the strength of West Pacific Subtropical High (WPSH) in summer during 1980-2004.Corresponding to the lower-level anomalous cyclonic circulation, the southwesterly of EASM was blocked by north wind in eastern China. Whereas the circulation anomalies of the above-mentioned quantities were weak during 1965-1979. The differences of sea surface temperature distribution in spring and summer between two periods of time are possible reasons for the changes in relationship and circulation.