The seasonal sampling was conducted in the West Lake section of Qiantang River from 2016 to 2018. A total of 31 species of fish belonging to 27 genera, 9 families and 7 orders were collected, among which the most species were Cyprinidae (21 species), accounting for 67.74% of the total species. According to ecological types, freshwater settlement, middle and lower layers, omnivorous fish are the main species. The dominant species were Carassius auratus, Hypophthalmichthys molitrix, Coilia nasus, Aristichthys nobilis, and Cynoglossus gracilis. Compared with the historical records, the decline of fish resources is more obvious, only the river and sea migratory fish and estuarine fish species decreased by 16 species, and there is the problem of fish miniaturization and singularity. The Jaccard similarity coefficient shows that the fish species composition is at a moderate dissimilarity level between any two years. The ABC curve also shows that the fish community was stable in 2016 and 2018, while it was disturbed in 2017.The Hypophthalmichthys molitrix, Carassius auratus and Hypophthalmichthys nobilis are the most important fish resources in this section, accounting for 49.65%, 20.14% and 16.19% of the total catch weight respectively.Although most of the traditional indigenous economic fishes in the Qiantang River are supplemented by long-term breeding and releasing, no dominant population has been formed in this section.Although the fish diversity index fluctuated seasonally and annually, the changes did not reach a significant level, and the seasonal changes of the fish community structure were related to the living habits of the fishes and the hydrogeological characteristics in the water to a certain extent.It is suggested to strengthen the protection of fish resources in this section of the river from the aspects of strengthening law enforcement, scientific breeding and releasing, improving habitat conditions and so on.In view of the lack of investigation into the fish community structure in the Qiantang River estuary section, it is suggested to carry out a comprehensive survey on the fish community and fish habitat in the Qiantang River estuary section continuously, so as to provide scientific basis for the formulation of detailed fish protection measures.