Abstract: Tibitan sheep serum protein was hydrolyzed by neutral protease,the influences of the temperature,hydrolysis time,p H value and the substrate / enzyme ratio on the degree of hydrolysis of Sheep serum protein were investigated.On the basis of single factor tests and response surface methodology,the optimal working parameters were worked out and tested.The optimum hydrolysis parameters were as follows: when the amount of enzyme was2400 U / g,hydrolyzing 5.5 hours at temperature 50 ℃ under p H6.8,and the degree of hydrolysis was 15.44 ±0.395% under the optimum conditions.The antioxidant activities of the hydrolysate was measured by the inhibiting effect on the scavenging ability of 1,1- diphenyl- 2- pycrylhydrazyl( DPPH),hydroxyl radical and superoxide radical.The antioxidant activities increased with increasing concentrations of test samples. The peptides exhibited high scavenging ability of DPPH,hydroxyl radical and superoxide radical with an IC50 value of 6.035,3.555 and2.872 mg / m L respectively.