In order to understand the characteristics of climate change in Hulun lake area and its effect on water area and water level of Hulun lake,using regression equation and Spearman analysis method to analyze the data of climate and change of water area during 1991-2009 in this area. The results showed that in recent 18 years, there was a warming trend that showed average temperature increased,precipitation decreased and evaporation increased; average temperature of fall increased significantly,which was the key factor affecting the average temperature. The average temperature showed a polarization trend that winter got colder and summer got hotter; water area and water level of Hulun lake decreased continuously in recent 18 years,and the decreasing rate accelerated obviously since 2000,the increasing temperature and evaporation were the main factors that affected the changes of water area and water level. Above all,significant increasing of fall average temperature was the main factor,which affected the changes of Hulun lake.