This paper documented the data of fish species systematically collected in the Daya Bay from 1980s on according to Nelson’s classification system and analyzed the diversity at different taxonomic levels.The inclusion index at taxonomic level(TINCL_i),taxonomic diversity(Δ⁺ and ∧⁺),relative abundances(R) and the similarity index(C)at Order and Family levels were used in this paper.TINCL_i is used first in this paper.The results indicated that the fish species in the Daya Bay belonged to 22 orders,94 families and 206 genera,and Perciformes is the major order .Analyzed by the inclusion index at taxonomic level,the average numbers of(families,genera,species),(genera,species) and (species) per order,family and genus are(4.27,9.36,14.55),(2.19,3.40) and(1.55),lower than those of the Dongsha Islands and higher than those in the East China Sea Continent Shelf.The values assumed the inverse proportion with the variation of latitude which demonstrated that the taxonomic diversity of fishes in lower-latitude was lower than the higherlatitude.The average taxonomic distinctness Δ⁺ and the variation in taxonomic distinctness ∧⁺ of the Daya Bay were tested in this paper by the PRIMER 5.2.The average taxonomic distinctness Δ⁺ was 62.2,and the variation in taxonomic distinctness ∧⁺ was 110.0.Compared the Δ⁺ with those of the East China Sea Continent Shelf and Dongsha Island,the genetic relationship of the composition of fish species in the Daya Bay was closer than the East China Sea Continent Shelf(65.7) and farther than the Dongsha Islands(55.2).Compared with the similarity index at the order level,the composition of fish species in the Daya Bay is similar to the Dongsha Islands,and similar to the East China Sea Continental Shelf at the family level.In order to increase the acquaintance of diversity in Daya Bay,this paper analyzed the composition of fish species at the species level.It can provide reference for the exploitation and conservation of fish species in the waters.