Tunny head immunological activity substance and method of preparing the same

An immunoactive substance extracted from tuna fish head and a preparation method thereof are provided. The method comprises the following steps: pretreatment, washing, crashing, protease digestion, hydrolysis with neutral protease and papain, oil-water separation, hydrolysate centrifugation, oil-water separation of filtrate, separation of protein hydrolysate and fish oil, fractional separation, and separation of protein hydrolysate by using ultrafiltration membrane, to obtain immunoactive substance of tuna fish head. The invention utilizes two proteases to hydrolyze proteins of tuna fish head and centrifugally separates peptide-rich protein hydrolysate with immunological activity. The protein hydrolysate can be further processed to oral liquid, capsules and tablets. Furthermore, the invention produces fish oil rich in polyunsaturated fatty acids, thereby realizing the comprehensive and high-efficiency utilization of tuna fish head. The immunoactive substance of tuna fish head can significantly improve humoral immunity and nonspecific immunity in mice and enhance the cellular immune function of mice.