In order to understand the fish community structure in Baiyangdian Lake and its relationship with the environmental factors. 30 sampling stations in Baiyangdian Lake were surveyed in May, August and October, 2019 and August and October, 2020. A total of 30 species of fish were collected, belonging to 12 families and 4 orders, among which Cypriniformes had the most, accounting for 56.67%, and 9 species had Index of relative importance IRI ≥ 500. Carassius auratus, Pseudorasbora parva, and Chanodichthys erythropterus were the dominant species. One-way analysis of variance (ANOVA) showed that the number of individuals, species, Margalef richness index (D), Shannon-Wiener diversity index (H') and Pielou evenness index (J') were significantly different in different months (P<0.05), and except for Pielou evenness index (J'), the other indexex were all the highest in May 2019 based on the SNK-q multiple comparison test. Non-metric multidimensional scaling (NMS) and one-way analysis of similarity (ANOSIM) showed that the composition of fish community overlapped and separated in different seasons (Global R=0.524). Abundance biomass comparison curve (ABC) showed that the fish community in May, August and October 2019 was slightly disturbed, and the fish community in August and October 2020 was moderately disturbed. Redundancy analysis (RDA) showed that water temperature, DO and chlorophyll a were the main environmental factors affecting the fish community in Baiyangdian Lake.