The climate over northwest China is always a big challenge for the Global Climate Models(GCMs) due to its complex topography and surface conditions,high-resolution dynamical downscaling simulation is usually considered as one useful method to achieve better model performance,both for the present climate simulation and the future projection. In this paper,a long term simulation over China for 1961-2100 was conducted using WRF model,which was forced by the output of MIROC5 from both historical and future projection experiment of the CMIP5 project,the horizental resolution is as high as 30 km. The model validation and future climate change was investigated focusing on northwest China. The results show that WRF has good performance in reproducing the regional temperature and precipitation distribution over northwest China. In the 21st century,surface temperature will continue to rise over northwest China,and the magnitude is larger in the end of 21st century than that in the middle. The annual mean temperature will rise faster in the southern part of Xinjiang than that in the northern part,and faster in the mountains than in the deserts. For the seasonal temperature change,the summer mean temperature will rise faster in the mountains,while the winter mean temperature will rise faster in the deserts. The precipitation over northwest China will decrease in the 21st century,especially in summer. The simulation indicates that the precipitation will decrease in the mountains,while increase slightly in the deserts.