To understand the status of biodiversity and community structure of fish assemblage in the Chaohu Lake, fishes were seasonally sampled from July 2017 to December 2018. Sampling was conducted in 9 sites which covered the three main types of fish habitat (estuary, nearshore shallow water area and open water area) in Chaohu Lake. A total of 52 species of fish, belonging to 7 orders and 15 families were collected. Among them, Cyprinidae had the largest number of species, accounting for 63.5%. Compared with historical records, 43 fish species were not captured. A large part of river-sea migratory fishes and river-lake migratory fishes disappeared while the no-native species Taenioides cirratus was newly recorded. Coilia nasus, Neosalanx taihuensis,Hypophthalmichthys molitrix and Aristichthys nobilis were recognized as the dominant species. Cyprinus carpio, Carassius auratus, Culter alburnus and Culter mongolicus were important species, and 22 species, including Paracanthobrama guichenoti and Siniperca chuatsi were rare species. The indicator species of different sampling sites were significantly different. Besides, significant variations of fish composition among sampling seasons and among sampling sites were detected, and fish composition among the sampling sites was more discrete than between the seasons. Analysis of the diversity index indicated that the richness, diversity and evenness of fish community were low. The range of Shannon-Wiener index (H') was 0.56-1.09, Simpson index (D) was 0.25-0.57, Margalef index (d) was 1.45-3.82 and Pielou index (J) was 0.19-0.32. On the temporal scale, the community diversity index in the summer 2018 was higher than that in other seasons. On the spatial scale, the Hangbu River estuary and the nearshore shallow water of east area showed higher community diversity index than other sampling sites. This study supplemented the basic data of fish community in Chaohu Lake and provided the scientific basis for fishery conservation and management.