A series of demersal fish sampling surveys were conducted around the Qiansan Islets from May 2013 toApril 2014, and the captured fish were identified to 22 species, 15 families, and 6 orders. Perennial rockfish species(PRS), including Hexagrammos otakii, Sebastes schlegelii, Hexagrammos agrammus, and Conger myriasterwere dominant in the studied area. Lateolabrax maculatus, Gadus macrocephalus, and Carangidae and Scombridaespecies were seasonal migration species. Results of a canonical correspondence analysis used to analyze theeffects of environmental factors on fish community structure suggested that the distribution of fish was mainlyinfluenced by bottom-water temperature and dissolved oxygen. Bottom-water temperature had a positive effect onbiomass of H. agrammus, Pterogobius zacalles, Paralichthys olivaceus, Sebastes hubbsi, Scomber japonicus, andSeriola dumerili biomass. Biomass of both G. macrocephalus and H. otakii was closely related with bottom waterdissolved oxygen, and G. macrocephalus was only distributed in deep water with high dissolved oxygen duringseasons with low temperatures. S. schlegelii, C. myriaster, and S. pachycephalus were widely distributed in thestudy area. The trophic level results determined using the stable nitrogen isotope method suggested that PRS werein the third and the fourth trophic levels, and that they were intermediate and top carnivores, whereas L. maculatusand G. macrocephalus were apex predators above the fourth trophic level.