Scale collagen polypeptide was prepared from Silver carp by microbial collagenase.The optimized digestion process by orthogonal test method was 40℃,6h and at pH7.5.SDS-PAGE showed the relative molecular weight of collagen polypeptide was mainly under 20.0 ku which was notably smaller than that untreated with collagenase hydrolyzation.The isoelectric point of as-prepared polypeptide was about pH 4.7,with a color of faint brown and fishy smell,which met the quality standard of the accredited full-cream milk powder.The scavenging activity(S.A.) of collagen polypeptide on free radicals was 15.89%,and its minimum inhibitory concentration(MIC) values for Staphylococcus aureus and Escherichia coli were 1.0mg/mL and 0.5 mg/mL,respectively.As indicated above,the collagen polypeptide was potentially a food additive in industry.