This paper was aimed to study the effects of glucose oxidase on average daily gain and intestinal flora in mice with moldy feed. A total of 130 KM mice, 18 to 22 g,were randomly assigned to 13 groups. The diet was added by 0, 10%, 20% and 30% moldy maize flour and 0, 0.1%, 0.3% and 0.5% GOD, respectively, and the experiment lasted for 60 days. The results showed as follows: compared with experimental control group, the average daily gain of mice fed with the diet added by moldy maize flour and 0.3% GOD for 60 days was significantly increased (P<0.05 or P<0.01). Addition of 0.3% and 0.5% GOD to the diet with 10% moldy maize flour significantly decreased the amount of bacterium E. coli (P<0.01), and increased the amount of Laetobacillus (P<0.01). When the mice were fed for 60 days with the diet added 10% moldy maize flour, GOD significantly decreased the amount of bacterium E. coli, and increased the amount of Laetobacillus (P<0.01). GOD decreased the amount of bacterium E. coli in mice fed with 30% moldy maize flour diet (P<0.05 or P<0.01), and 0.3% GOD was proper. Addition of 0.3% and 0.5% GOD increased the amount of Laetobacillus in mice fed for 60 days (P<0.01). This study demonstrates that GOD can ameliorate the effects of moldy diet on the growth of mice. Addition of 0.3% GOD is suggested on the condition that aflatoxin B₁ dose in diets is not more than 67.77 μg/kg.