Largemouth bass(Micropterus salmoides)has become one of the important famous freshwater fishes in China since the success of their artificial breeding in 1985.However,iced trash fish from offshore is still the main feed during the culture process of largemouth bass,and long-term use of iced trash fish not only puts pressure on the resources and environment,but also brings some of the original ocean pathogenic microorganisms into freshwater aquaculture area.Replacement of iced trash fish by artificial feed is an inevitable trend in the industrial development of largemouth bass,but in fact,the progress of extensive use of artificial feed has been slow.It's reported that demand for fish feed or nutrition is closely related to composition of the intestinal flora of fish,and differences of fish diets also affect the composition of fish intestinal microflora.So,to explore the nutritional needs and feed configuration of largemouth bass,based on intestinal microflora,is a valuable new exploration.In this paper,intestinal microflora of different largemouth bass including feeding iced trash fish and artificial diet were examined to assess intestinal bacteria community structure using the technology of PCR-denatured gradient gel electrophoresis(PCR-DGGE).The results showed that,microflora composition similarity between iced trash fish group and artificial diet group was 24%.Compared with the iced trash fish group,the diversity of intestinal microflora of artificial diet group decreased.The analysis of the common and specific bands from two groups of largemouth bass demonstrated that,the common intestinal bacteria of both groups include Rhodospirillaceae,Clostridium,Cyanobacterium,Edwardsiella hoshinae and Stenotrophomonas maltophilia; the specific intestinal bacteria of iced trash fish group were Bacteroides,Carnobacterium,Weissella and Plesiomonas; the specific intestinal bacteria of artificial diet group were Flavobacterium,Cetobacterium somerae,Leuconostoc citreum,Brevundimonas diminuta.In sum,compared with iced trash fish,artificial diet reduced the diversity of intestinal microflora and also inhibited the quantity of probiotics of largemouth bass.It's speculated that slower growth of largemouth bass feeding artificial diet may be related to the decline in the ratio of Bacteroides to Firmicutes.The results of this study suggested that,in the future,the probiotics such as Bacteroides could be added to artificial diet for improving absorption of artificial diet,and further promoting the growth and nutritional absorption of largemouth bass.