【Abstract】Objective To explore the mechanism of dendrobium nobile polysaccharides on the effection of myocardium injury in type 2 diabetic rats, and provide a reference for the development of Dendrobium nobile and further to treat the diabetic myocardium injury. Methods Forty male SpragueDawley rats were randomly divided into the normal group, model group and low dose, medium and high dose treatment group and benazepril treatment group. The rats were sacrificed at the end of the treatment. HE staining was used to observe the histopathology of the heart. The blood glucose, insulin, cardiac function and oxidative and antioxidant capacity of the rats were measured by kits. The expression of MMP-1 and MMP-9 in heart tissue was detected by realtime quantitative PCR and Western Blot. Results The rats had a normal diet in the normal group, and they were active and hairy, but the model group had obvious symptoms of hyperpinement and polyuria. Dendrobium nobile polysaccharide had obvious effect on improving the above symptoms. HE staining could found normal in the normal group, while the model group had obvious fibrous rupture, the nucleus volume increased. Compared with the model group, Dendrobium nobile polysaccharide middle dose group, high dose group and benazepril group had a significant improvement. The levels of blood glucose, insulin resistance index, AST, aHBDH, CTnl, SOD, GSH and TAOC in the model group were significantly higher than those in the normal group (P＜0.05). MDA and insulin of Dendrobium nobile polysaccharide middle dose group, high dose group and benazepril group were significantly higher than those in the normal group (P＜0.05). The levels of SOD MDA, GSH and TAOC of Dendrobium nobile polysaccharide middle dose group, high dose group and benazepril group were significantly higher than those of the normal group (P＜0.05). The levels of MMP1 and MMP9 in the model group were significantly higher than those in the normal group (P＜0.05). The expression MMP-1 and MMP-9 of Dendrobium nobile polysaccharide and benazepril group significantly increased (P＜0.05). The expression MMP-1 and MMP-9 of Dendrobium nobile polysaccharide high dose group was significantly higher than that of benazepril group(P＜0.05). Conclusion High fat diet induced to the rats with type 2 diabetes mellitus has a significant myocardial damage and abnormal cardiac function. Dendrobium nobile polysaccharides can significantly improve the functional of damaged. The effect is superior to benazepril. Dendrobium nobile polysaccharide could improve the antioxidant capacity of rats and increase the expression of MMP1 and MMP9 in the heart tissue.