Abstract: A feeding trial was conducted to evaluate the maximum level of substitution of dietary fish meal by various proportions of soy protein concentrate and peanut bran supplemented with coated lysine and methionine for Penaeus monodon. The shrimp (mean initial weight 1.27±0.02 g) were assigned to the 18 plastic cylinders(500 L) and fed with six diets containing 40% crude protein and 7% crude fat at a temperature of (30±1.0) ℃ for 56 days. The six test diets contained 30%(F0, control), 27%(F1), 24%(F2), 21%(F3), 18%(F4), 15%(F5) fish meal respectively. The results show that the shrimp fed with F0 gain the maximum WG (245.02%) and SGR (2.58% · d^-1) values, which are significantly higher than those fed with F3~F5(P < 0.05).The feed conversion ratio of the shrimp fed with F1 is the lowest and significantly lower than those fed with F3~F5(P < 0.05). The survival rate of shrimp fed with F4 is the lowest and significantly lower than that fed with F0~F2(P < 0.05), but without differences with other diets(P>0.05). The different level of fish meal substituted by plant proteins have no significant effects on the whole body composition of shrimp (P>0.05). The SOD activity in hepatopancreas of the shrimp fed with F2 is the highest and significantly higher than that of shrimp fed with F0 (P < 0.05), but without differences with other diets (P>0.05). The activity of SOD in muscle is the highest in F5 and significantly higher than any other groups (P < 0.05). The activity of ACP in muscle of the shrimp fed with F1 is the highest and significantly higher than those of shrimp fed with F2~F4(P < 0.05). The activity of LSZ in muscle is the highest in F4 and F5 and significantly higher than F0~F3(P < 0.05). Based on the data of weight gain and specific growth rate, the plant feedstuffs supplemented with coated amino acids can replace dietary fish meal in P. monodon by 20%, and the non-specific immunity of shrimp is enhanced with the increase of the dietary plant proteins.