To evaluate the immune function ofSardinops?sagaxoligopeptide (SSO); the oligopeptide was prepared fromSardinops?sagaxby using enzymatic hydrolysis; centrifugation; filtration and spray drying; and its chemical composition was analyzed. Animal experiments were conducted to study immunological enhancement effect by the evaluation techniques of healthy food. The results showed that the molecular weight of SSO was mainly below 1000 u; accounting for 66.4% of the total dry weight; and glutamic acid; lysine; aspartic acid and leucine were higher in the amino acid content. SSO was rich in selenium; which was 1.66 mg/100g. Compared with the negative control group; the proliferation rate of lymphocytes in normal mice was significantly higher in the positive control group and the SSO high-dose group (p<0.05); and the assay result of cellular immune function was positive. The spleen index and the number of plaque in normal mice could be improved significantly in the positive control group; the SSO high-dose group; the SSO medium-dose group and the SSO low-dose group (p<0.05); and the assay result of humoral immune function was positive. The positive control group; the SSO high-dose group; the SSO medium-dose group and the SSO low-dose group had no significant influence on the organ indexes of normal mice (p>0.05); and the assay result of mononuclear-macrophage function was negative. The positive control group and the SSO high-dose group could significantly increase the activity of NK cells in normal mice (p<0.05); and the assay result was positive. In conclusion; SSO can improve immune function in normal mice.