Abstract: Aspergillus oryzae was cultivated with Pinctada martensii on solid culture medium, then it was hydrolysed.Reducing power, DPPH radical scavenging activity, oxygen radical absorbance capacity (ORAC) were used to evaluate the hydrolysate's antioxidant activity.Total nitrogen, ammonia nitrogen, peptide and color were used to stand for the laws of protein degradation, the relationship between protein degradation's laws and hydrolysate's antioxidant activity was also researched.The results showed that the antioxidant activity of the fluid showed an increasing trend with the increasing hydrolysis time, the reducing power was 2.20 times as much as before.DPPH radical scavenging activity was 1.55 times as much as before.ORAC reached the maximum of 2834.67μmol Trolox/g (36h) , which was 1.13 times as much as the equal quality of the glutathione.The total nitrogen was 1.89 times as much as before, the ammonia nitrogen was 2.57 times as much as before.As for the change of colour, both of dark substance and the rate of color showed an increasing trend with the increasing hydrolysis time.According to the correlation analysis, the relevance between the change of ammonia nitrogen and the antioxidant activity was significant.