Abstract: Abstract：Lactic acid is a kind of organic acid which was excreted by lactic acid bacteria. This article is to determine the maximum concentration excreted by Lactobacillus acidophilus. Lactic acid in 4 different concentration were drenched to 4 teams respectively, 12.89ul/ml、30ul/ml、60ul/ml、90ul/ml. The result was obtained throw body temperature, clinical symptom, dissecting detection，biochemistry test and pathological section. The change in blood serum was tiny after 60ul/ml Lactic acid drenching. No lesion had be found in 60ul/ml for small intestine. Lactic acid in 60ul/ml is the suitable concentration to establish Lactic acid animal model in mouse intestine.