Releasing regular of flavor compounds during enzymolysis of mussel (Mytilus edulis) protein and the structure of seafood flavor peptides were investigated with amino acid analysis, ultrafiltration, gelchromatography, RP—HPLC, and UHR—Q—TOF. The results indicated that, during enzymolysis, molecular weight of peptides reduced. The amount of free flavor amino acid and TMA increased. The amount of peptidyl flavor amino acids increased then decreased. It’s advantageous for peptides with low molecular weight to be released at low pH conditions. The total carbohydrate varied little. The total acid reached the maximum in 1 h and at 50 ℃, respectively. Under the conditions that enzymolysis time of 2 h, enzymolysis temperature of 50 ℃ and enzymolysis pH of 6.5, the percentage of low molecular weight peptides, total acid, total carbohydrate, and flavor amino acid were in fairly high level. The flavor peptides form mussel (Mytilus edulis) were determinated as peptides in a low molecular weight below 1 kDa, with unique amino acid sequences of Cys-Ser-Val-Gln-Asp-Gln or Gln-Ala-Val-Asn-Phe-Thr, and taste threshold of 0.1 mg/mL.