Abstract:  This paper investigates the impact of climate change on water resources of Jialing River catchment in upper Yangtze River basin, China. The reference potential evaporation (ET0) and crop evapotranspiration (ETc) are calculated by using the Penman-Monteith equation, multiplying a corp coefficient Kc,respectively, Annual actual evapotranspiration (AE) is computed by annual area precipitation minus annualrunoff. The water balance model is calibrated. According to the future scenarios of 2050 and 2100, the model is used to calculate annual runoff. For the most disadvantage conditions, the annual runoff will decrease 23.0% to 27.9 in 2050, and it will be 28.2% to 35.2% in 2100. By extrapolation, the 2050 and 2100, annual runoffs are equivalent to about 1 in 7 year and 1 in 12. year drought respectively. The effects of water resources decreasing on development in the basin are described, and uncertainties of simulated results are discussed.