Double, three factor-test and orthogonal designs were employed to study the effect of protective agent, membranolytic agent, activating agent, denaturalization temperature and denaturalization time on SOD extracted from pig and bovine blood block. The results of double and three factor-tests show that the variance between pig and bovine blood block was obviously significant (P<0.01). The mixture protective agent was better than single, the best was 1.5% galactosylglucose + 0.5% β-cyclodextrin + 0.25% PEG, and the better membranolytic agent was 3% Triton X-100 + 0.5% n-butyl alcohol for bovine blood, and 3% Triton X-100 for pig blood. The optimal dosage of protective agent was 20% of blood block weight, the optimal dosage of membranolytic agent was 15-20% of blood block weigh, and the best optimal dosage of activator was 2.5%. The best optimal combination of orthogonal experiment for bovine blood block was A2B2C2, and the best optimal combination of pig blood was A1B1C2. Under those conditions, the activity of SOD exceeded 3000 U/mg protein.