Yarlung Zangbo River is one of the most important rivers in the southwest river source area, it is the longest plateau river in China, the cradle of the birth and development of Tibet civilization, and also an international water system. It is of great significance to study its water resources utilization and water environment protection. This paper compared different river extraction methods, including the normalized difference water index, multi-band spectral correlation threshold method, maximum likelihood classification method and object-oriented classification method, based on Landsat images, and combined with remote sensing and GIS technologies. The study area is Yarlung Zangbo River, one of the main rivers in southwest river source region. Meanwhile, river changes have been analysed based on upstream and midstream of Yarlung Zangbo River extracting results of four images in different periods. The result shows that object-oriented classification method has advantage of removing mountain shadow, its accuracy of river extraction is the highest, and Yarlung Zangbo River area shows a decreasing trend from 2000 to 2016, and there are some changes of watercourse in midstream as well.