Abstract: Objective:To study the hypoglycemic effect and mechanism of polysaccharides from Anemarrhena asphodeloides with molecular weight of 30~100 kDa on diabetic SD rats induced by streptozotocin(STZ). Methods:STZ-induced diabetic rats were divided into normal group,high blood glucose group,the metformin group,molecular weight of 30~100 kDa Anemaran group;Drugs were administered intragastrically for four weeks. Body weight,fasting blood glucose,total cholesterol(TC),triglycerides(TG),high-density lipoprotein(HDL-C),low-density lipoprotein(LDL-C)and fasting insulin(FINS)were examined on all groups,and pancreatic tissue changes were determined by HE staining. Results:Compared with the high blood glucose group,the molecular weight of 30~100 kDa Anemaran group of blood glucose,TC,LDL-C and insulin resistance index were significantly decreased(p<0.01),TG and serum insulin were decreased(p<0.05),the inhibition rate of blood glucose was 62.4%,the body weight and HDL-C were significantly increased(p<0.01);HE staining showed that Anemaran could reduce the selective damage of STZ to islet cells of diabetic rats,and repair the islet cells after being destroyed. Conclusion:The molecular weight of 30~100 kDa Anemaran could obviously decrease the blood glucose and lipid levels of diabetic SD rats,improvement of insulin resistance and repair of damaged islet cell tissue might be one of the mechanisms.