With the output result of global climate model,the essential factors of river basin scale precipitation and temperature are obtained through downscaling the relevant statistical downscaling scale-model. A temperature-evaporation regression relationship and Xinanjiang hydrological model are established according to the measured data,and then the variation trend and amplitude of the water resources in Ganjiang River Basin under the future climate changing scenarios is estimated and analyzed with coupling simulation and MK trend. The study result shows that the changing trends of the meteorological and hydrological factors, such as annual precipitation,annual evaporation,annual runoff,etc. ,under different future emission scenarios are mainly significantly increased. The multi-year mean values of the annual precipitation,annual evaporation and annual runoff in the future are to be increased to a small extent with the maximum increasing amplitude of 13. 81% of the annual runoff if compared with those of the relative reference period. The intra-annual variations of precipitation,evaporation and runoff have obvious seasonal characteristics, while the non-uniforms of the increase of runoff during flood period and decrease of runoff during non-flood season are aggravated,which are possibly to increase both the pressures from the flood control and the water supply during dry season in future to a certain extent.