Abstract: Dangqu River, one of the sources of the Yangtze River, is the core part of the protection area for the Source of Three Rivers(Yangtze River, Yellow River, and Lantsang River). It is still a blank area of scientific research because of high elevation, marshy tracts and complex watersheds for scientific observation and research. There are some doubts about its position in the Yangtze River source. In this paper, some main scientific survey results in the past few decades are analyzed and compared. According to the comprehensive results of scientific investigation by the Yangtze River Scientific Research Institute in 2014, the position of Dangqu river in the source region of Yangtze River and the characteristics of river basin, landscape and wetland are analyzed. Problems on the position of Dangqu River basin are clarified and some suggestions on the division between the upstream and downstream, as well as ecosystem protection measures are put forward.