Abstract: Objective To investigate the influence and curative effect of bifidobacterium infantis（B.infantis） on intestinal mucositis of cancer rats induced by chemotherapy. Methods A model of cancer rats by subcutaneous injection of dimethyl hydrazine with rectal mucosa of cancer cells was created， and experimental rats were randomly divided into three groups： control group（saline）， chemotherapy group（5-FU+oxaliplatin）， bifidobacterium infantis group（5-FU+oxaliplatin+B.infantis）. The changes of diarrhea， body weight， villus height， crypt depth and levels of the proinflammatory factors IL-1β， IL-6 and TNF-α were recorded. Results In 41 mice, 12 mice consctracted tumor successfully, including 3 mice in control group, 5 mice in chemotherapy group and 4 mice in bifidobacterium infantis group. In the model of cancer rats， after 72 hours treatment，B.infantis administration prevented the loss in body weight（P＜0.05）. B.infantis reduced the occurrence of diarrhea（1.43±0.53 vs. 2.43±0.79，P＜0.05）. Compared to the chemotherapy treated rats， B.infantis could attenuate the injuries of the morphology of intestine.B.infantis-treated rats in a villus height［（379.37±53.80）μm vs.（335.33±89.54）μm，P＜0.05］ and a crypt depth［（219.22±38.05）μm vs.（331.24±69.24）μm，P＜0.05］. Intestinal IL-1β， IL-6 and TNF-α levels， which increased significantly in all rats receiving chemotherapy， were lowered by B.infantis administration except TNF-α level. However， there were no significant differences in plasma IL-1β， IL-6 and TNF-α levels. Conclusion The Bifidobacterium infantis effectively reduce intestinal injury due to chemotherapy-induced intestinal mucositis in cancer rats.