In order to find out the characteristics and distribution of dominant fish assemblages in kelp beds of Gouqi Island,we sampled the fish assemblages in kelp beds and sandy beach every month from February 2009 to January 2010.The composition,biological characteristics and prey habits of dominant species were compared,separately.The results showed that the dominant fishes in kelp beds dominated by larger macroalgae Sargassum horueri or smaller algae,as Ulva pertusa were the same,i.e. Sebastiscus marmoratus, Agrammus agrammus and Nibea albiflora.The assemblages of S.marmoratus,with younger age and smaller size,have frequent prey activity along the coast and large variety in abundance.The strong recruitment of stock comes from the high reproduction of female,which were early sexual maturation and more than male in abundance.Prey variety of objects survived from the overfishing.The assemblages of both A.agrammus and N.albiflora were younger age and affected by the migration assemblages from open sea.The growth of above three species was different owing to the different feeding habits and prey objects.Meanwhile,due to the food conversion at the different stages of development,body variety and predation pressure from the top predator, S.marmoratus and N.albiflora will alter their choice in habitats for different utilization. A.agrammus doesn’t change into prey objects in its life,so the main activity habitats are affected by Caprellidea,the major feeding target.