Based on the NCEP/NCAR monthly SLP reanalysis data,the interdecadal changes and propagating features of the Antarctic Circumpolar Wave(ACW) during 1952-1998 are studied in this paper by use of the first recovered field of the complex empirical orthogonal function(CEOF) expansion.The results show that the southeast Pacific is a key area for researching ACW.Then the activity index of ACWs over the southeast Pacific(EPAI) is defined.It is revealed that there is a close relation between the EPAI in autumn and the next summer rainfall over China.When the autumn EPAI appears an abnormally positive phase,namely while the positive SLP anomalies occurs over the southeast Pacific,the Australian high becomes stronger than normal in the next spring and summer.Furthermore,the enhancement of the cross-equatorial flow and the shift of the west Pacific subtropical high lead to the summer precipitation pattern of more rainfall in South China and less rainfall in the Changjiang-Huaihe valley in the next year,thus confirming that the ACW is a strong interannual variation signal for the abnormality of summer rainfall over China.