Abstract: In this paper,2°×2° mean monthly COADS grid data from 1950 to 1987 are used to compute the averages and deviations of the temperature,pressure,zonal wind,special humidity,cloud and the components of heat budget on the equatorial Pacific surface (5°S-3°N).In the processes of EI Nino,the pressure gradient and trade decreased on the equatorial Pacific surface,the sensible and latent heat exchanges increased,the net longwave radiation and incident solar radiation decreased and the net gain (loss) of heat reduced (increased) on the central and eastern equatorial Pacific surface.In the Processes of La Nina the circumstances were oposite.Finally,two feedback mechanisms of EI Nino-La Nina cycle which include the dynamic,thermal and hydrological processes in the coupled air-sea system are sumrnerized.