Abstract: Thirty-two healthy one-day-old AA broilers were divided into 4 groups in this study: Group A (control) with basic diet, Group B with basic diet and antibiotic (100 mg/kg of Colistin), Group C with basic diet and 500 mg/kg of Chinese Medicine (Youkangbao), and Group D with basic diet and 500 mg/kg of sodium butyrate.After seven weeks, the mucosal structure of small intestine was observed.Results were as follows: (1) There were significantly differences in the morphological change of mucosa of small intestine among A, B, C, and D groups.(2) The lengths of villi, V/C value, thickness of mucosa, and thickness of muscular layer in experimental groups were larger than that of control group. (3) The value of V/C decreased from duodenum to ileum in control group, but it was larger in ileum than that of the jejunum in experimental groups.However, the value of V/C was larger in experimental groups compared with control group.This study indicated that three feed additives could improve mucosal structure of small intestine in broiler; Sodium butyrate and Chinese Medicine (Youkangbao) have the feasibility to substitute of antibiotic in improving mucosal structure of small intestine.