To investigate the trophic structure characteristics of fish communities in Yangcheng Lake, resource surveys were conducted in summer (July), autumn (October) 2017, and spring (April) 2018, and the carbon (δ¹³C) and nitrogen (δ¹⁵N) values of fish communities and their trophic structure were analyzed using stable isotope technology. The results of the study showed that 42 species of fishes, belonging to 5 orders, 10 families, and 33 genera were collected from the lake. The mean values of δ¹³ , δ¹⁵N and trophic level of Yangcheng Lake fishes were (?24.85±1.77)‰, (15.34±2.19)‰, and 3.06±0.64, respectively, among which δ¹⁵N and trophic level showed significant differences (P<0.01) in fish feeding and seasonality, whereas the value of δ¹³C did not show significant differences (P>0.05). The Layman’s community-wide metrics showed that there were seasonal differences in the trophic structure of fish communities in Yangcheng Lake, wherein the trophic level length, basal food source, total ecological niche space, overall community density, trophic niche distribution range, and core ecological niche space of the fish in spring were greater than those in summer and autumn, with a high diversity of food sources and low degree of trophic redundancy. A gradual upward trend from summer to autumn in 2017 and then to spring 2018 was noted. This study initially constructed a continuous trophic spectrum of fish in Yangcheng Lake, enriching the study of the Yangcheng Lake ecosystem in terms of fish community trophic structure, with the aim of providing a reference for lake ecological management and sustainable fishery development.