The potential evapotranspiation of Hexi regions was calculated based on the Penman-Monteith equation. Slope analysis was employed to assess the main meteorological factor trends from the year of 1975 to the year of 2012.The spatiotemporal patterns of surface humidity changes in the Hexi region were discussed using the humidity index.The results indicated that the maximum temperature and the mean annual temperature had increased significantly,while the wind velocity had decreased significantly in this region.With the increase of the elevation,the precipitation and the humid index increased significantly,while the potential evapotranspiration decreased significantly.In addition,sensitivity of ET_0 to climatic changes under different climate scenarios was also evaluated.The results indicated that the potential evapotranspiration was positively related to the average temperature,average wind velocity and the sunshine duration,while it was negatively related to the relatively humid and air press.The variation percentage in the potential evapotranspiration caused by the changes of the individual meteorological factors(average temperature,average wind velocity, the sunshine time,relatively humid,air press)was 41.1%,22.9%,19.1%,16.4%and 0.5%,respectively.