This paper analyzes the characteristics of super typhoons(STYs)over the western North Pacific(WNP)from 1965 to2005 and describes the seasonal variability of STY activity.The relation between STY activity and the El Nio-Southern Oscillation(ENSO)as well as the possible reason for the influence of the ENSO on STY activity are also investigated.The results showed thatabout one fifth of the tropical cyclones(TCs)over the WNP could reach the rank of STY.Most STYs appeared from July to Novem-ber while there was a highest ratio between number of STYs and total number of TCs in November.Most STYs appeared east of thePhilippine Sea.In El Nio years,affected by sea surface temperature(SST),monsoon trough and weak vertical wind shear,TC for-mation locations shifted eastward and there were more STYs than in La Nia years when the affecting factors changed. This paper analyzes the characteristics of super typhoons (STYs) over the western North Pacific (WNP) from 1965 to 2005 and describes the seasonal variability of STY activity. The relation between STY activity and the El Nio-Southern Oscillation (ENSO) as well as the possible reason for the influence of the ENSO on STY activity are also investigated. The results showed thatabout one fifth of the tropical cyclones (TCs) over the WNP could reach the rank of STY.Most STYs appeared from July to Novem-ber while there was a highest ratio between number of STYs and total number of TCs in November. Most STYs had east of the Philippine Sea. El Niño years, affected by sea surface temperature (SST), monsoon trough and weak vertical wind shear, TC for-mation locations shifted eastward and there were more STYs than in La Nia years when the affecting factors changed.