Abstract: To investigate the characteristics of the fish community structure in South Lake Taihu after the implementation of fishing ban,this study conducted surveys in May,July,September,and November of 2022 and 2023. A total of 55 fish species were collected and identified,which belonged to 39 genera,12 families,and 8 orders. Among them,Cypriniformes was the most abundant order with 40 species,accounting for 72.73% of the total. In terms of ecological types,resident species (76.36%),omnivorous fish (40%),and pelagic fish (40%) were dominant in South Lake Taihu. The dominant species comprised of three fish types,of which,Coilia nasus was the primary dominant one,and accounted for 78.90% in quantity and 16.23% in weight. It was followed by Aristichthys nobilis and Hypophthalmichthys molitrix. In terms of biodiversity,the average Margalef richness index in South Lake Taihu was 4.13,and the average Shannon-Wiener diversity index was 1.13. In terms of temporal variation,the fish species diversity index in July was higher than that in other months. The Abundance/Biomass Comparison (ABC) curve analysis indicated that South Lake Taihu remained in an undisturbed state,with a relatively stable fish community structure. Compared to the pre-fishing-ban period,this study observed a reduction in the trends of fish miniaturization and younger age structures,along with increases in species count and diversity indices. The community exhibited stability and low susceptibility to disturbance,demonstrating the initial effectiveness of the fishing ban. To consolidate these outcomes and ensure long-term ecological benefits,it was recommended to sustain the fishing prohibition efforts,strengthen the protection of native fish resources,and enhance regulatory enforcement. This study provided scientific references for optimizing fisheries resource management in South Lake Taihu and refining the implementation of fishing-ban policies.