<p>The proposed China-Nepal railway passes through rivers on the southern slope of the Himalayas, characterized by sharp incision and a dense distribution of various types of knickpoints. To enhance the understanding and practical relevance of knickpoint landforms, this paper takes the Gyirong corridor section of the China-Nepal railway as the research area. Firstly, combined with the morphological characteristics and causes of the knickpoints, different types of knickpoint characteristics and geomorphic evolution effects are proposed. Then, according to the requirements of railway route selection at the geomorphic scale, an integrated knickpoint identification method is proposed, combining the gradient threshold method, steepness index, and field investigation. Finally, based on the analysis of Gyirong-Tsangpo river knickpoints, the railway geological route selection principles based on knickpoint effects on landform evolution are proposed. The results show that this method can significantly reduce field workload and determine the influence range of the knickpoint with high accuracy and efficiency. Thus, a new method for identifying river knickpoints that matches the accuracy requirements of the principal route selection stage is established using only publicly available data. This research provides a new method for determining the area and extent of river stability and provides a scientific basis for the alignment of the China-Nepal railway.</p>