Under the background of global warming,it is important to analyze the regional water suitability. Aridity index of the upper and middle reaches in Taoer River where is located in northeast China's Inner Mongolia and Jilinwas calculatedduring the period 19612012. The trends of mean temperature,wind speed,sunshine hours,relative humidity,precipitation and were analyzed using the climatic trend rate and Mann - Kendall trend analysis. The sensitivity of to meteorological factors was analyzed by calculating the sensitivity coefficients of to them and the change ofwas studied by analyzing the relative changes of them. The results showed that mean temperature and precipitation had increasing trends,while wind speed,sunshine hours,and relative humidity and had decreasing trends. The most sensitive variable wasprecipitation,followed by relative humidity,wind speed,mean temperature, and sunshine hours. Moreover,the contributions to the change of in descending order were:wind speed, mean temperature,precipitation,relative humidity,sunshine hours. The contributions of mean temperature and relative humidity were positive,but otherswere negative.