Abstract: In the paper,according to ocean-atmospheric data up to now, a new strong ENSO event which human follow with interest, starting from March 1997,has been diagnosed.The result indicates SSTs continue to increase 1-4℃ in equatorial mid-eastern Pacific area, meanwhile SSTs in tropical Indian Ocean also warms.The southern oscillation index maintains lower value but it doesn't get as strong as that in 1982/1983 year. Lower equatorial Pacific troposphere trade-wind weakened, corresponding to intensified upper troposphere easterly wind.The OLR minimum value center and OLR maximum negative anomaly center move towards the east. Convection over the mid-equatorial Pacific intensified. The evident drought and flooding anomaly occurred in the region around Pacific. If this ENSO event develops in the future, it will be the strongest ENSO event in the century. We compared with last two strong ENSO event in 1982/1983 and 1986/1987 year. Authors' purpose is to enhance understanding of the strongest signal of tropical Pacific ocean-atmosphere anomaly, a large-scale background field condition is given for making yearly climate tendency prediction.