Abstract: Trypsin was used to digest oyster meat restrictively. The effects of hydrolysis degree on the sensory score,distribution of peptide molecular weight and composition of free amino acid in oyster hydrolysates were studied. The results showed that with the increase of hydrolysis degree,the umami,sour and sweet taste of oyster hydrolysates began to increase and then decrease,while the salty and bitter taste increased. The ratio of peptide molecular weight>10 kDa and 5~10 kDa decreased gradually,while 3~5 kDa began to increase and then decrease,and 1~3 kDa and <1 kDa increased gradually. The hydrolysates with the highest ratio of peptide molecular weight <1 kDa and 1~3 kDa was DH62.02%. The contents of free amino acids,total free amino acids and essential amino acids in the six hydrolysis degree oyster hydrolysates increased with the increase of hydrolysis degree. The content of flavor amino acid,sweet amino acid and bitter amino acid increased with the increase of hydrolysis degree,and aromatic amino acid began to increase and then decrease. With the increase of hydrolysis degree,the amount of TAV>1 amino acids in six hydrolysates increased gradually. The TAV values of glutamic acid in the six hydrolysis degree oyster hydrolysates were all greater than 1,and the TAV values gradually increased with the increase of hydrolysis degrees.