Glacier length is a major parameter to describe glacier change and climate change. In this study, the methods of extracting glacier mainstream line and glacier center line are integrated to extracting glacier length. This integrated method is based on Gaofen-1 satellite remote sensing data and digital elevation model (DEM), and is tested upon the Purog Kangri ice field on the Tibetan Plateau. First, the glacier boundary is extracted by the band threshold method and visual interpretation. Then the glacier length is extracted by the glacier mainstream line method, the glacier center line method and the integrated method, respectively. The results show that the mainstream line method has the higher accuracy when the glacier area is larger than 1 km~2,while the center line method has the higher accuracy when the glacier area is smaller than 1 km~2. The integrated method has the highest accuracy, 97.9%, with high efficiency.