Abstract: Based on the data of anomalies of monthly mean sea level of the Pacific ocean,the sea level fluctuations in the Pacific during the 1986-1987 El Nino are analyzed and compared with that in 1982-1983 counterpart.It is shown that the sea surface topography not only has a response to the wind field quite well,but also can better reflect the propagation of warm water mass.Therefore,the sea level is a effective indicator for monitoring ENSO event.An evolutive model of anomalies of monthly mean sea level in Pacific ocean at different phases of ENSO episode is given.