Based on the data of precipitation, temperature, evaporation, etc., from meteorological stations over the drainage areas of the Shaanxi Ankang Reservoir, an analysis is made of the characteristics of climate change over in the drainage areas of the reservoir. The results indicate that annual precipitation reduced year by year; annual average temperature was increasing year by year; annual evapotranspiration had a negative trend; annual and main flood season precipitation, rainy days, heavy rain days, the probability of extreme heavy precipitation and evapotranspiration appeared much less after reservoir impoundment than before. The extent of warming in winter was most obvious. The main flood season and annual precipitation, average temperature, and evapotranspiration in winter before and after impoundment show significant differences. The natural runoff of the Hanjiang River had a negative trend in the past 45 years and rainfall influenced runoff significantly.