Abstract: Based on the date from some weather and hydrometric stations,the corresponding relationship between El Nino,the air temperature,the precipitation and the runoff in the Qilian mountain is analyzed. The result shows that the effects of El Nino are different in the different time and zones.That is,when El Nino occurs,the air temperature rises,but the precipitation and the runoff decrease in the whole mountain area,especially in the east and middle parts.In the next year when El Nino occurs,however,though the air temperature rises,the precipitation and the runoff in the east and middle part of the Qilian mountain region don't decrease as much as in the year when El Nino occurs,and there is no obvious correlativity between El Nino,the temperature,the precipitation and the runoff in the west part of Qilian mountain region.