Abstract: Immunoreactive substances can stimulate the immune system of shrimps, and enhance the immunocompetence of animal. The influence of egg yolk immunoglobulin on the immunity-related enzyme activities and WSSV resistance of shrimps has not been reported. In this research, we fed basic diets containing three levels(1%, 0.5%, 0.1%)(M/M) of Ig-Guard(shrimp) to Litopenaeus vannamei continuously for 20 days, and the basic diets as blank control. Then detected phenoloxidase(PO), acid phosphatase(ACP) and lysozyme(UL) activities of the serum and superoxide dismutase(SOD) activity of the muscle, and protein concentration of the serum and the muscle on days 5, 10, 15 and 20. All the immune parameters of the test groups measured were higher(P<0.05) than the control group. After 20 days, we fed white spot syndrome virus(WSSV) to shrimps, and recorded the mortalities of challenging test in seven days. The relative percent survival(RPS) value of the test groups was 17.95%, 23.08%, 35.90%. This experiment indicates that Ig-Guard(shrimp) can effectively enhance the shrimps’ immunity-related enzyme activities, and it can also promote shrimps’ WSSV resistance. Based on the results of immunity-related enzyme activities and cumulative mortality, the enzyme activities of the lower concentration group was higher than the higher concentration group, and it’s cumulative mortality was lower, so we suggests that feed the lower concentration Ig-Guard(shrimp) properly is reasonable.