Abstract: In order to study the function of the fish habitat conservation area of the tributary Bachu River after the construction of Batang hydropower station in the upper reaches of Jinsha River, the monitoring of fish resources in the main stream below Batang dam and the tributary Bachu River was carried out in 2021, and the fish species composition and community structure were analyzed by using diversity index and multivariate statistical methods. A total of 11 fish species were collected in the main stream and tributary, including 4 endemic species and 3 alien species in the upper reaches of the Yangtze River. The dominant species in the main stream are Schizothorax, and the dominant species in the tributary are two small-sized fishes, Schizopygopsis malacanthus and Triplophysa stenura. Fish community of nine sampling locations were partitioned into two groups at the 43.53% Bray Curtis similarity level. We attributed the difference between these two groups to the different dominant species in the main river and the tributary Bachu river according to SIPMER analysis. The biodiversity index of the two sampling locations near the confluence of Bachu river were the highest, which may be related to the complexity of the habitat at the confluence. It is suggested to strengthen the protection of the habitat at the confluence. At the same time, restoring the connectivity of the upper reach of the confluence of Bachu river may prolong the migratory distance of Schizothorax, which is conducive to expand its population scale.