Myostatin is an important member of the transforming growth factor (TGF) family that functions to regulate muscle development and growth in animals, The purpose of this study was to characterize and predict function of the myostatin gene of Haliotis diversicolor supertexta which is an important aquaculture shellfish. In this study, the myostatin (Hs-MSTN) cDNA of H. diversicolor supertexta were cloned and characterized by rapid amplification cDNA ends (RACE) methods. The full length of Hs-MSTN cDNA sequence consists of 3 755 bp containing a 5' untranslated region (UTR) of 324 bp, a 3' UTR of 1 985 bp, and an open reading frame of 1 446 bp encoding a protein with 481 amino acid residues, with a calculated molecular mass of 54.96 ku, and the theoretical isoelectric point of 9.41, The structure of Hd-MSTN included a putative signal peptide (1-17 aa), a TGF-β propeptide domain (157-367 aa) and a conserved TGF-β domain (379-481 aa). Multiple sequence alignment results revealed conservation of the RRPR proteolytic site and nine conserved cysteines of the Hs-MSTN with MSTN from other animals, and two propeptide proteolytic sites RQRR (120-124 aa) and RYRR (235-239 aa) were found. Phylogenetic analysis showed that the Hs-MSTN gene was clustered in the same subgroup with the H. rufescens, Quantitative real-time PCR detection results indicated that the Hs-MSTN genes were expressed widely in adductor muscle, mantle, gonad, liver, gill, foot and the highest expression level was observed in the adductor muscle, mantle, foot, and Hs-MSTN transcript was widely detected in early developmental stages:unfertilized egg, fertilized egg, 4-cell embryos, 8-cell embryos, gastrulae, larvae, juvenile stage, and the higher in fertilized egg, in 4-cell embryos and 8-cell embryos and the expression level increases in gastrulae, larvae and decreases in juvenile stage. Our results indicate that MSTN is involved in muscle growth regulation of H. diversicolor supertexta.