The first principal component of the Southern Oscillation Index (SOI) is used as the intensity of annual SO. A composite analysis is made of typhoon activities over the Northwestern Pacific in the El Nino/anti-El Nino year and the year after. It is found that the characteristic of the correlation between ENSO and typhoon activities in June and before differs from that after June In the El Nino year the average number of typhoons developing over the Northwestern Pacific is greater than normal from January to June,smaller from June until next June and greater from then until next December.The date of the first typhoon in the year following El Nino will be postponed.The opposite is true for the anti-El Nino year. In most cases the first typhoon will appear in January. Moreover, the relations between ENSO and the number of severe typhoons landing on China’s coast are examined, which are of much use to the long-range forecasting of typhoon activities and to the early diagnosis of El Nino events.