Abstract: Introducing SSTA in the equatorial eastern Pacific into the GCM during January-March,a simulation study about ENSO(EI Nino and La Nina) influences on East-Asian monsoon activities is completed.The results show that the influences of ENSO on the afterward monsoon activities in East Asia are in existance owing to atmospheric low frequency oscillation excited by SSTA.After El Nino event,in the summer,the subtropical high in the western Pacific will be stronger and its location will be to north and west,the precipitatoin is less in Eastern China,particularly in Huabei region;In the winter,the aerotrough in East Asia will be deepening,the winter monsoon will be stronger.After La Nina,in the summer,there is a subtropical high center over the lower reaches of Changjiang River,so that the precipitation is less in ChangJiang-Huai River basin;in the winter,the aerotrough will be weaker,the winter monsoon is weaker.It is also shown that the influence of El Nino is stronger than that of La Nina on the climate and their influences are not the exact opposite.