In order to explore the effect of soybean peptide on brooding chicken,in the experiment,three hundred and sixty 1-day-old healthy chickens were randomly divided into four groups and each group with three repeats,every repeats with 30 chickens. Chickens in control group were fed with basal diet,and those in experimental B,C,D groups were fed with the basal diet supplemented with 0.4%,0.8%,1.2% soybean peptide.And the growth performance,immune function and blood biochemical indexes of different treatments were determined.The experiment lasted for 42 days.The results showed that adding soybean peptide could improve the daily weight of brooding chicken,and decrease the ratio of feed to meat.The average weights of group B and group C were higher,of which 42 days’ weights respectively were up to 350.95 g and 349.95 g,and were significantly higher than that were group A.The ratio of feed to meat of group C was the lowest(2.48),which was significantly lower than that group A.Adding soybean peptide could improve the immune organs index of brooding chicken. Addition of soybean peptide showed a trend of increasing blood Ca content,decreasing total cholesterol content and increasing alkaline phosphatase,glutamic-pyruvic transaminase and glutamic-oxalacetic transaminase activity of brooding chicken.The optimum addition amount of soybean peptide was 0.8%.