Myostatin or GDF-8,a member of the transforming growth factorβ(TGF-β)surperfamily,has been demonstrated to be a negative regulator of myogenesis and inhibited myoblast proliferation during cell cycle and myogenic differentiation in animals.In present research,two SNPs sites(C-1453T and T+33C)were identified from total MSTN gene in larghmouth bass by using PCRSSCP technique and sequencing; The mutational site of C-1453 was between the regions of E8 box and Octamer(+).the mutation of T+33C was situated in the first extron of the MSTN gene,however the mutation of the first extron has not changed the encoded amino which belonged to the synonymy mutation.The three kinds of genotypes per mutation site were obtained by PCRRFLP method and the genotype frequency of the mutation was caculated in the population of 128 individuals.A general linear model was used to statistically analyze associations of MSTN gene polymorphisms with major growth traits respectively,and the results indicated that there was no significant difference(P>0.05)by all genotypes of single mutation site.Six diplotypes,with the minor allelic frequencies of above 3%,were constructed based on two SNPs in the experiment population.The means of diplotype D2 were over other diplotypes and the means of diplotype D5 were lower other diplotypes in terms of body width,body height,body length,body weight,and snout length therfore associations analysis indicated that there were significant associations between diplotype D2 and D5 in the five growth traits of largemouth bass.The study implies that diplotypes D2 and D5 of MSTN gene could be used as the moleculer genetic marker for selection breeding.