Abstract: In this paper,the probabilities of both the positive departure of sea surface temperature(SST)at the Pacific Ocean and the negative geopotential departure in 500 hPa of the Northern Hemisphere in month and season from last to next year were computed for ten E1-Nio years and six anti-El-Niño years,which were defined by Ansell.It is evident that the main characteristics of the SST and the geopotential height in each season during the same period are contrary between El-Niño year and anti-El-Niño year.The life cycle for either El-Niño or anti-El-Niño can be divided into seven stages,i.e.portent,occurrence,development, prosperity,stability,weakness and extinction stages.There exists an opposite PNA teleconnection pattern in 500 hPa between them on the evolution of the circulation type,and there is the factor of change toward the opposite direction as they are happened.The representative season and district of El-Niño were defined objectively.The spectral analysis for the indexes of both El-Niño and PNA shows that the most obvious evidence is 42-month periodic variation,the index of El-Niño is backward for 4.15 months compared with that of PNA.On the other hand,the predictive equation for the El-Niño index in autumn is established by these predictors selected by the 500 hPa geopotential height of the Northern Hemisphere.The effect is satisfactory.