Abstract: In order to understand the structural characteristics of fish community in the Cibi Lake in Eryuan County, and provide scientific basis for formulating fishery resources protection plans, a total of four surveys were conducted to analyze the fish community structure in the Cibi Lake in March, June, September and December 2022. The results showed that a total of 5 701 fish samples weighing 61 557.8 g were collected, and 15 species were identified, belonging to 4 orders, 7 families and 13 genera. Among them, the Carp family had the largest number of fish species, with 8 species, accounting for 53.33% of the total number of species. The composition of fish species was dominated by lake settlement species, Carassius auratus, Ctenogobius giuriuns, Hemiculter leucisculus, Acheilognathus chankaensis, and Cyprinus carpio were the dominant species in the Cibi Lake throughout the year, accounting for 80.60% of the total number. The Margalef’s richness index ranged from 0.83 to 1.58, the Shannon-Wiener’s diversity index based on the number of individuals and Pielou’s evenness index ranged from 0.79 to 1.53 and 0.47 to 0.77, respectively, and the Shannon-Wiener’s diversity index based on the biomass and Pielou’s evenness index ranged from 0.78 to 1.41 and 0.45 to 0.79, respectively. The Margalef’s richness index, Shannon-Wiener’s diversity index based on the number of individuals and Pielou’s evenness index were significantly different between seasons (p<0.05), while the Shannon-Wiener’s diversity index based on the biomass and Pielou’s evenness index values were not significant between seasons (p>0.05). The stability of fish communities was highest in autumn, followed by summer, and the lowest in spring and winter.