In this study,two types of El Nio events are distinguished and the correlations between the respective precipitation,temperature,and runoff are analyzed by a 5-point moving average method.Also,changes of the temperature,precipitation,and runoff from mountainous watersheds of the Hexi Corridor region caused by these two types of El Nio events from 1959 to 2005 are studied by the anomaly analysis method.The results indicate that the Hexi Corridor region is strongly influenced by El Nio:rising temperatures and decreasing precipitation and runoff are features of the first El Nio pattern,while decreasing temperature and increasing precipitation and runoff characterise the second pattern.The responses of temperature to El Nio events are stronger in plains than in mountain regions,but the responses of precipitation are obvious in both types of regions.The response of runoff to El Nio events is lower than the precipitation and temperature response because runoff from mountainous watersheds has a complex generation and concentration process. In this study, two types of El Nio events are distinguished and the correlations between the respective precipitation, temperature, and runoff are analyzed by a 5-point moving average method. Also, changes of the temperature, precipitation, and runoff from mountainous watersheds of the Hexi Corridor region caused by these two types of El Nio events from 1959 to 2005 are studied by the anomaly analysis method. The results that results that the Hexi Corridor region are strongly influenced by El Nio: rising temperatures and decreasing precipitation and runoff are features of the first El Nio pattern, while decreasing temperature and increasing precipitation and runoff characterise the second pattern. responses of temperature to El Nio events are stronger in plains than in mountain regions, but the responses of precipitation are obvious in both types of regions. the response of runoff to El Nio events is lower than the precipitation and temperature response because runoff from mountain ous watersheds has a complex generation and concentration process.