Under different pretreatment methods of heat,smashing and their combination,the collagen peptide of crass carp scale was obtained after the processes of enzymatic hydrolysis,centrifugalization and freeze drying.The yield and properties of specimens were compared and analyzed.Results showed that the average values of the nitrogen recovery,degree of hydrolysis,amino-N production and anti-oxidant activity in vitro were significantly different between different pretreatment groups (P<0.05).The relative molecular weight and distribution did not vary significantly with pretreatment methods.Considering the yield and properties of end-products,the ideal pretreatment method is heat and smashing for collagen peptide extracted from crass carp scale.