An experiment was conducted to investigate the effects of adding liquid Lactobacillus preparation on growth performance, digestive enzyme activities and non-specific immunity of Litopenaeus vannamei. Four hundred and fifty fingerlings of Litopenaeus vannamei (initial average weight: 1.42 g) were randomly allotted to 5 groups with 3 replicates and 30 shrimp in each replicate. Five diets were added 0 (control group), 0.5%, 5%, 10% and 15% Lactobacillus preparation in basal diet, respectively. The experiment lasted for 8 weeks. The results showed that growth performance was improved in shrimp fed the 10% Lactobacillus preparation diet. Weight gain ratio and specific growth ratio were increased by 7.13% （P＞0.05） and 4.23% （P＞0.05） compared with the control group, respectively. Feed conversion ratio was reduced by 8.38% （P＞0.05） compared with the control group and significantly lower than that of shrimp fed the 5% Lactobacillus preparation diet （P＜0.05）. Protease and amylase activity in the hepatopancreas and intestine of trial groups were improved compared with the control group. Protease and amylase activity in the hepatopancreas and amylase activity in the intestine in 5% group were the highest and significantly different from those in the control group（P＜0.05）, and protease activity in the intestine in 5% group was significantly higher than that in the control group （P＜0.05）. The activity of lysozyme in the serum of all trial groups was higher than that in the control group, and lysozyme activity in 10% and 15% groups was significantly higher than those in the control group（P＜0.05）. The activity of phenoloxidase (PO) and superoxide dismutase (SOD) and serum protein levels were not different among all groups. And then serum protein levels of trial groups were higher than that in the control group. The activity of PO in the trial groups except 0.5% group was increased compared with the control group. The activity of SOD in the trial groups except 15% group was improved compared with the control group. The activity of peroxidase in control group was the lowest and significantly lower than that in 10% group. In conclusion, adding Lactobacillus in basal diet could promote growth performance, increase digestive enzyme activities and enhance non-specific immunity in the shrimp.［Chinese Journal of Animal Nutrition, 2010，22（1）:228-234］