Abstract: In this paper,the variability of the Asian summer monsoon circulation during the ENSO period is diagnostically analysed.Evidence suggests that every member of the Asian summer monsoon system changed in varying degrees, even,oppositely,during El Nino events and La Nina events. Then, on the basis of the summer rainfall in east China analysed using EOF, both region and extent of impact of the eastern tropical Pacific SSTA on the summer rainfall in East China are analysed. This impact is related closely with the development phase of ENSO cycle,being most notable in the middle lower reaches of Yangtze River and South China.