Abstract: To investigate the antidiabetic effect of Lactobacillus rhamnosus on type Ⅱ diabetic mice.L.rhamnosus was administered to mice with dose of 109CFU/d for 12 weeks.Results showed that L.rhamnosus could slow down weight loss in mice with diabetes and significantly decrease fasting and postprandial 2h blood glucose, and then significantly (p<0.05) improved the glucose tolerance to alleviate insulin resistance.L.rhamnosus significantly (p<0.05) reduced glycosylated hemoglobin, endotoxin, tumor necrosis factor-alpha, interleukin-6 and malondialdehyde compared with the control group.Values of insulin, interleukin-10, glutathione peroxides, glutathione, and superoxide dismutase were increased significantly ( p < 0.05) .Islets of Langerhans in the L.rhamnosus group were significantly protected from destruction compared with those in the control group.Studies had shown that L.rhamnosus could reduce the blood glucose and alleviate symptoms due to protect islets of Langerhans to be destroyed and improve the immunoregulatory properties and oxidative stress in type Ⅱ diabetic mice.