With global warming， precipitation patterns and distribution patterns are changing all over the world. Among them， the precipitation changes in arid areas are particularly noticeable. Under the global warming， precipitation and water content in the atmosphere have increased in Northwestern China. However， this "warm and wet" is an improvement of the humid degree in arid areas， which does not change the basic climate characteristics of drought and less rain. The precipitation pattern in Northwestern China is fundamentally different from that in Eastern China， and the increase of precipitation is mainly due to the increase of extreme and short-term convective precipitation. In addition， the increase of precipitation mainly occurs in inland river basin， and the arid areas in the basin could not solve the ecosystem problems with abundant water. It is necessary to make clear the difference of drought properties between arid Northwestern China and arid and semi-arid Yellow River basin. The main sources of water resources in Northwestern Hexi Corridor are precipitation and ice and snow resources in mountainous areas. The relationship between precipitation in Northwestern China and snow and ice resources in Qilian and Tianshan mountains should be explored. A scientific and rational understanding of the increase of precipitation in Northwestern China is the premise for the proper allocation and use of water resources in Northwestern China and the scientific development of ecological civilization.