In this paper,shrimps of Fenneropenaeus chinensis with the body weight of(0.33±0.020 4) g(SF group)and(2.07±0.184) g(MF group)respectively and Marsupenaeus japonicus with(0.25±0.018 1) g(SM group)were fed with gammarid Ampithoe valida to determine the effects of gammarid on growth and antidisease ability of the shrimps.The results were as follows:(1)Compared with shrimp pellet feed,gammarid can improve SGR of shrimps in MF and SM groups and can improve survive rate of shrimps in SM group too.(2)Gammarid can raise the total number of blood cells of shrimps in SF and SM groups significantly(P＜0.05).(3)Gammarid can improve total protein level in blood of three shrimp groups significantly(P＜0.05)and can also improve hemocyanin of shrimps in SF and SM groups significantly(P＜0.05).(4)Gammarid can improve activity of LSZ of M.japonicus.(5)Gammarid can improve activity of PO and SOD of shrimps in MF and SM groups significantly(P＜0.05).(6)Gammarid can improve the relative activity of POD of shrimps in SF and SM groups significantly(P＜0.05).(7)There is a linear relationship between the total score of healthy index and the time during which shrimps were all killed by WSSV(R²=0.948 9).The results show that:Gammarid can improve growth and antidisease ability of the F.chinensisandM.japonicuscompared with pellet feed and the best time for gammarid as nature food is when the shrimps are larvae.