Abstract: In this paper, in order to investigate the causes for the for mation of ENSO Cycle, we first examine the relationship of El Nino and La Nina events with the westerly wind anomalies over the western Pacific warm pool.On this basis, the roles of the Asian and Aust ralian winter monsoons in the formation and progress of the westerly windanomalies are studied.Finally, we analyze the associations of the Asian and Australian winter monsoons, the westerly wind anomalies and the El Nino and La Nina alternations with the propagating anomalies of the Southern and Northern Oscillation.