Aim To investigate the effect of arecoline on the injury of endothelium dependent relaxation induced by high glucose of isolated thoracic aorta of SD rats and explore the potential mechanism. Methods Organ baths in thoracic aortic rings of SD rats were used to investigate the effect of different concentration arecoline on the injury of endothelium dependent relaxation induced by high glucose. The levels of nitric oxide (NO) and malonaldehyde (MDA) and the activity of superoxide dismutase (SOD) in the isolated thoracic aorta rings were measured. The M receptor inhibitor atropine and nitricoxide synthase inhibitor N-nitrio-L-argine methyl ester (L-NAME) were used in the study. Results Compared with the control group,endothelium dependent relaxation induced by acetylcholine of isolated thoracic aorta of SD rats was significantly decreased in high glucose group. The injury of endothelium dependent relaxation induced by high glucose was inhibited by arecoline in concentration-dependent manner. But the effect of arecoline was abolished by atropine and L-NAME. The levels of NO and the activity of SOD were decreased and the levels of MDA was increased in the isolated thoracic aorta rings by high glucose,but the effect of high glucose was reversed by arecoline. Conclusion Arecoline prevents the injury of endothelium dependent relaxation induced by high glucose,which mechanisms may be related to activation of M receptor,increase of NO and inhibition of oxidative stress induced by arecoline.