Ni o Index (Sea-Surface Temperature Indices) and SOI（the Southern Oscillation Index）are two main indices used in monitoring and defining and predicting ENSO events. Based on Ni o3.4 Index since 1950, 15 El Ni o events and 11 La Ni a events have been identified. An El Ni o events results in heavy rainfall, even floods in the equatorial central and eastern Pacific, South America and south China, but scarce rainfall even severe droughts in India, Indonesia, Malaysia, eastern Australia. At the same time, rainfall is reduced over northern area of east China in summer,autumn and all year, tropical cyclone frequencies in the Pacific and Atlantic and landing China typhoon frequencies are decreased. It is warm over southeast Canada and northern U.S.A in winter, low temperature over eastern Asia, warm in winter and cool in summer over China. But during La Ni a events, this results in droughts in central and eastern tropical Pacific, tropical cyclone or typhoon frequencies in the Pacific and Atlantic and landing China typhoon frequencies are increased . The rain band in China during the high-water season is to the north . It is hotter in summer and colder in winter over China.