Objective: To investigate the effect of oat?-glucan on colon flora and its function in mice. Method:126 Kunming mice(23-25g)were divided into seven groups (18 mice in each). The group 1 and 2, 3 and 4 ,5 and 6 were respectively administered oat?-glucan (OG2600 , OG340 and OG5) at dose of 0.25 and 0.5g/(kg bw?d)daily for 28 d. The control group received the equal volume of normal saline. Bifidobacterium , Lactobacillus and Enterobacillus were monitored in colon after oral administration of oat ?-glucan at 14 d, 28 d and 35 d (after terminating oat?-glucan admimistration for 1 w) . The contents of short chain fatty acids (SCFA) in colon were analyzed by GC and cell proliferation in colonic mucosa epithelium by FCM in each group. ResuIts:The numbers of Bifidobacterium , Lactobacillus compared with the control were significantly increased and Enterobacillus strains were decreased in experimental groups. Oat ?-glucan had the function of regulating intestinal flora and the effect was related to molecular weight and dosage. The contents of acetate, propionate, butyrate were higher in the group 2, 4 and 6 compared with the control (P