Abstract: To determine the optimum supplemental level of irradiation\|soybean meal for broiler diet， this experiment was conducted to investigate the effects of irradiation\|soybean meal on performance， serum biochemical indexes and the immune organ index in broilers. Five hundred and sixty healthy broilers with near weight were randomly allocated to 4 groups with 4 replicates per group and 35 chickens per replicate. Control group was fed with a corn\|common soybean meal basal diet， and test groups were fed with the basal diet with 5%， 10% and 15% irradiation\|soybean meal（based on diet） instead of corn\|common soybean meal， respectively. The experiment lasted for 42 days. The results showed as follows: （1） The average daily gain and average daily feed intake of broilers among groups were not significantly different （P>005） during 1-21days， while the average daily gain of broilers fed with 5% irradiation\|soybean meal diet increased significantly （P<0.05） during 22-42 d and 1-42 d. The feed to gain ratio of groups fed with irradiation\|soybean meal was significantly reduced during 1-42 day （P<0.01）. （2） Compared with the control group， the total serum protein of broilers fed with diets with 10% and 15% irradiation\|soybean meal significantly increased （P<0.05）. （3） The diets with 10% and 15% irradiation\|soybean meal could significantly improve the serum T\|SOD activity （P<0.01）. （4） The thymus index of broilers in group supplemented with 10% irradiation\|soybean meal was higher（P<0.05）. It was concluded that the irradiation\|soybean meal supplementation in the basal diet could promote the growth of broilers， and improve the immunity and oxidation resistance.

Key words: irradiation\, soybean meal, broilers, production performance, immune function, antioxidant function