Abstract: The climatic variations since 1961 over the upper Yellow River were analyzed in this paper.It indicated that the tendency of annual air temperature rising was very obvious from the med and late 1980s,especially the annual air temperature in 1998.From 1990s,the spring and summer temperature were rapidly increased.The precipitation dit not have significant variation tendency in the annual and autumn,tended to increas in the winter and spring,and to decrease in the summer.The effects of the annual flow,rainfall,air temperature,and droughty climate on the water resources were andyzed.The results showed that the water resoures were decreased,and the reductive tendency was very obvious since the late 1990s.This tendency consisted with that of the summer precipitation.It indicated that the reductive precipitation during flood season was the dominant factor of climate for reducing flow of the upper Yellow River.