According to the characteristics of high protein content in mackerel, the antioxidant peptides were prepared by ultrasonic assisted enzymatic hydrolysis. The content of polypeptide was measured by the biuret method, and the DPPH(1,1-two-2-three nitro phenyl hydrazine) free radical scavenging rate was used as the evaluation index to explore the technological conditions for preparing mackerel antioxidant peptides. The results showed that the optimal preparation conditions for enzyme solution was as following:...