The Haxilegen No.51 Glacier is located on the northern slope of Eren Habirga Mountains in the Tianshan Mountains,the headwater of the Haxilegen River which is a tributary at the upper reaches of the Kuytun River.In order to measure and research the change of the Haxilegen No.51 Glacier,we established 26 rods on the glacier in August 1999,with 2 control points around the glacier and 3 control points in the glacier terminus for measuring the change.The changes in the glacial terminus and glacial surface velocity from 1999 to 2006 were measured by using GPS and traditional technique.The results reveal that the glacial area has reduced by 0.123 km~2 during 1964 - 2006,by 0.083 km~2 and 0.040 km~2 during the periods of 1964 - 2000 and 2000 - 2006,respectively.That is,the reduction of glacial area became more and more marked,and the annual percentage of area changes (APAC) for the glacier was 0.19%,lower than an average of other glacier's areas in the Tianshan Mountains.The glacier terminus has retreated for about 84.51 m,and the average annual shrinkage was 2.01 m.The surface velocity of the glacier in 1999 - 2006 was slower.The mass balance of the glacier increased with the rise of the elevation, but the inter-annual variation was smaller during 7 years.During the period of 1964 - 2010,the thickness of Haxilegen No.51Glacier thinned by about 10 m,with an average annual rate of 0.22 m.Comparison between the No.1 Glacier at the headwater of the Urumqi River and Haxilegen No.51 Glacier at the headwater of Kuytun River in recent decades showed that the tendency of Haxilegen No.51 Glacier melt was weaker as a whole.