Ghrelin is one of the vital brain-gut peptides in vertebrates. In 1999, a noval 28-amino acid gut-brain peptide named ghrelin was first isolated from the mammalian stomach. Similar to the synthetic molecules of growth hormone secretagogues, ghrelin was proved to be an endogenous ligand for growth hormone secretagogue receptor and involved in growth hormone secretion, food intake, carbohydrate metabolism, and energy homeostasis. So, ghrelin gene is a potential candidate gene for fish growth traits. This study detected the polymorphism of the promoter of largemouth bass (Micropterus salmoides) ghrelin gene by DNA sequencing in 327 individuals, for exploring the association between the polymorphism of ghrelin and growth traits of largemouth bass. Two single nucleotide polymorphism (SNP) mutations were identified (S1:A-642C, S2:A-639C) of the gene. The genotype and gene frequency of 327 largemouth bass were further assayed with the method of SnaPshot, at site S1, there three kinds of genotypes named AA, AC and CC, the gene frequency were 0.067, 0.685 and 0.248 respectively. There were only two genotypes AA and AC on the locus of S2, of which gene frequency were 0.850 and 0.150 respectively. Genetic structure was analyzed by POPGENE32 software, the results showed that the two locus were in Hardy-Weinberg equilibrium, the effective number, expected heterozygosity and observed heterozygosity of S1 were 1.9362, 0.4843 and 0.6831 respectively, which of S2 were 1.1620, 0.1396 and 0.1508. The sites of S1 and S2 formed five diplotypes(D1, D2, D3, D4 and D5). Association analysis showed that individuals with genotype AC were significantly higher than those of individuals with genotype CC in body depth and total length at site S1. At site S2, the individuals of genotype with AA significantly showed a higher value on head length compared to the genotype of AC. The five diplotypes consisted of the two SNPs were different on some growth traits, the body weight, total length and body depth of diplotypes D1 showed significantly higher than those of D3. And diplotype D1 also showed a significantly higher value of body weight, body width and body depth compared with genotype D4. The SNP markers founded in ghrelin gene promoter would be candidate genetic markers, and it suggested that S1:A-642C and S2:A-639C could be two molecular markers for providing helps to the molecular marker assisted breeding of largemouth bass.