The processing residues of Atlantic salmon (Salmo salar) contain abundant proteins and are of high value for further utilization, while abandoning them would be a waste of resources and might cause environmental pollution. Thus it is significant to research the preparation of antioxidant peptides from Atlantic salmon processing residues with its endogenous proteases. A preliminary study of proteases from Atlantic salmon viscera showed that there were mainly 3 types of endogenous proteases which were most active at pH value of 2.0, 6.0, and 9.0 respectively, and the alkaline protease with optimal activity at pH 9.0 had the highest specific activity level. Atlantic salmon processing residues protein were hydrolyzed by endogenous proteases to produce the antioxidative hydrolysates. The degree of hydrolysis and the total antioxidant activity were compared to find the best single factors; among the single factors studied, temperature, initial pH and time had significant effects on the total antioxidant activity of enzymatic hydrolysis solution (P<0.05), and the optimum hydrolysis conditions were determined by L16 (45) orthogonal array design as follows: temperature 35°C, dosage of enzyme 0.7mL/50mL, material-to-solvent ratio 0.7g/50mL, pH value 9.0, and time 7h, under which the total antioxidant activity and degree of hydrolysis were 258.29U and 15.00%, respectively. In conclusion, it is feasible and practical to prepare antioxidant peptides from Atlantic salmon processing wastes using its endogenous proteases.