Abstract: In order to investigate the differences in basic nutrients between different orders and species of freshwater fish,the basic nutrients of 13 species of freshwater fish in four orders had been studied. Results showed that the difference of water and fat content of freshwater fish was statistically significant. The fat content of the Perciformes was 56.0% lower than that of the Cypriniformes,and the moisture content of the Cypriniformes was 5.7%,12.4% higher than that of the Acipenseriformes and the Siluriformes,and the moisture of Perciformes was 7.9%,14.7% higher than that of the Acipenseriformes and the Siluriformes. From the point of view of fish species,the differences in protein,moisture,ash and fat content of different fish species were statistically significant. The protein content of Siniperca chuatsi fish was 20.3% higher than that of Cyprinus carpio,Megalobrama amblycephala,Oreochromis spp.,Pelteobagrus fulvidraco,Ctenopharyngodon idellus,Lepomis gibbosus,Ophiocephalus argus. The ash content of Ctenopharyngodon idellus was 2.0% and higher than that of the 11 other freshwater fish. The fat content of Cyprinus carpio,Ctenopharyngodon idellus and Silurus asotus was higher than that of the other 10 species. The Ophiocephalus argus had the lowest fat content of 0.1%.The 13 kinds of freshwater fish were rich in essential amino acids,ranging from 41.8% to 43.3%,which were in line with the recommended ratio of the ideal model of FAO/WHO(EAA/TAA:40%). The principal component analysis of 17 amino acids contained in 13 kinds of freshwater fish was carried out,and the cumulative contribution of the 2 principal components was 87.659%. The amino acid scores of 13 freshwater fishes were:Oreochromis spp. > Lepomis gibbosus > Cyprinus carpio > Silurus asotus > Siniperca chuatsi > Lateolabrax japonicus > Ophiocephalus argus > grass carp > Megalobrama amblycephala > Pelteobagrus fulvidraco > Aristichthys nobilis > Carassius auratus > Polyodonspathala. Oreochromis spp. Scores was the highest. According to the factor score,13 kinds of freshwater fish were clustered into 3 categories by cluster analysis. The first typewas Oreochromis spp.,Lepomis gibbosus and Cyprinus carpio.The second type was Carassius auratus,Megalobrama amblycephala,Aristichthys nobilis,Ctenopharyngodon idellus,Lateolabrax japonicus,Ophiocephalus argus Cantor,Siniperca chuatsi,Silurus asotus and Pelteobagrus fulvidraco. The third category was Polyodonspathala.This experiment provided basic research materials for the development and utilization of freshwater fish,aiming to provide people with a better source of dietary freshwater fish.