Variation characteristics of potential evapotranspiration (ET_0) has important significance in water cycle research and water resource assessment in the background of global climate change in Danjiangkou reservoir area. ET_0 and dry index (DI) measured by Penman-Monteith model were analyzed based on the measured meteorological data during 1970-2009,which came from the National Meteorological Center public network. The results showed that: (1) Annual precipitation with a mean value of 839.9 mm decreased with the increment of annual series,and the annual,rainy season and dry season precipitation decreased by 14.3,4.5 and 9.0 mm/(10a) respectively. (2) Annual ET_0 with a mean value of 860.0 mm increased with the increment of annual series,and the annual,rainy season and dry season ET_0 increased by 12.2,10.2 and 2.9 mm/(10a) respectively. (3) Annual DI with a mean value of 1.07 increased with the increment of annual series,and the annual, rainy season and dry season DI increased by 0.02,0.17 and 0.31 mm/(10a) respectively. (4) ET_0 and DI had significant negative correlation with relative humid, and significant positive correlation with mean wind speed and sunshine hours. The climate in Danjiangkou reservoir area had a drought trend stem from the decrease of precipitation and increase of ET_0 in the recent 40 years.