Abstract: Based on fisheries resources surveys conducted in the Panzhihua section of the Jinsha River from 2013 to 2017, variation characteristics of fish biodiversity before and after impoundment of the Guanyinyan Hydropower Station were statistically analyzed in present study. A total of 65 fish species belonging to 3 orders and 10 families were identified during the five-year study period, 20 of which were endemic to the upper reaches of the Yangtze River. Of the 65 fish species, 12 were detected in each year, all of which were lotic fishes except Pseudobagrus vachelli. Abundance/biomass comparison (ABC) curves and W statistics revealed that fish communities were seriously affected after impoundment and operation of Guanyinyan Hydropower Station in October 2014. Cluster analysis (CA) and non-metric multidimensional scaling analysis (NMDS) showed that fish species composition could be divided into two groups: Group I (2013-2014) and Group II (2015-2017), but one-way analysis of similarity (one-way ANOSIM) indicated no significant difference between the two groups. According to similarity percentage (SIMPER) analysis, species that decreased in abundance in group II were mainly those spawning drifting eggs such as Coreius guichenoti and Rhinogobio ventralis. Therefore, to better conserve natural fish resources in the Panzhihua section, a comprehensive strategy including on-site conservation, off-site preservation, ecological operation, artificial reproduction and releasing should be developed.