Hydropower development had a significant effect on the fish habitat and their biological diversity.To evaluating the current status and changes of fishery resource of Wuqiangxi Reservoir 20 years after the completion of a hydroelectric dam, the fish resources were investigated during April of 2012 to March of 2014. Results showed that a total of 86 fish species (including 5 introduced) were collected, belonging to 7 orders, 18 family, 58 genera. Cypriniformes were dominant, accounting for 66.28% of the total species. There were 54, 67 and 52 fish species found in the end,reservoir and downstream reach of Wuqiangxi Reservoir, respectively. The jaccard similarity coefficient showed that the fish communities of the reservoir area were highly similar to those at the dam sector, and moderately dissimilar to those at the reservoir tail.It was also the same moderately dissimilar between the reservoir tail and the dam sector. With regard to ecological type,fish communities in the Wuqiangxi Reservoir showed diversification types, the sedentary, omnivore and demersa species were dominant, accounting for 68.60%, 55.81% and 41.86% of the total species, respectively. Despite the species of the catches in various sections were different, the species number such as Pelteobagrus fulvidraco, Carassius auratus, Cyprinuscarpio and Culter mongolicus occupied a higher proportion in each section. The yield and dimension of the reservoir area were higher than those of the other two sections, and the catches showed miniaturization significantly. We compared the fish species number of the reservoir area between the pre-and post-dam periods,the fish species reduced 46 species and dropped 40.71%. Some common economic fishes such as Ochetobius elongatus, Onychostoma sima, Brevifilis brevifilis and Leiocassis longirostris were not found.