The experiment was conducted to investigate the effects of Bacillus licheniformis on the growth performance, antioxidant indices and blood biochemical parameters of broiler chickens. Two hundred and forty 1-day-old broiler chickens were randomly divided into four groups with four replicates in each group and 15 chickens per replicate. The chickens in control group (group Ⅰ) were only fed basal diet, and those in other groups (groups Ⅱ, Ⅲ and Ⅳ) were fed basal diet supplemented with 50, 100 and 200 mg/kg Bacillus licheniformis, respectively. The experiment lasted for 28 days. Average daily gain and daily feed intake were measured, and blood antioxidant enzymes and biochemical parameters were determined on the 28th day. The results showed that the average daily gain in group Ⅱ was significantly higher than that in group Ⅰ (P<0.05), and the F/G in group Ⅱ was significantly lower than that in group Ⅰ (P<0.05), and the average daily feed intake in group Ⅱ was higher than that in group Ⅰ (P>0.05). The activities of SOD and GSH-Px in serum of group Ⅱ were significantly higher than those of group Ⅰ (P<0.05), and the content of MDA in serum of group Ⅱ was significantly lower than that of group Ⅰ (P<0.05). The contents of uric acid and BUN in serum of group Ⅱ were significantly lower than those of group Ⅰ (P<0.05). The contents of albumin and total protein in serum of group Ⅱ were significantly higher than those of group Ⅰ (P<0.05), but there was no difference in the activity of alkaline phosphatase and the content of cholesterin in serum among groups (P>0.05). It was concluded that 50 mg/kg Bacillus licheniformis could improve the growth performance and antioxidant function, and reduce the contents of uric acid and urea nitrogen in serum, and increase the contents of total protein and albumin in serum of 28-day-old broiler chickens.［Chinese Journal of Animal Nutrition, 2010，22（4）:1019-1023］