Objective To study the protective effects of sevoflurane at different anesthesia depths on periperative myocardial ischemia in coronary heart disease patients undergoing noncardiac surgery.Methods 96 patients with coronary undergoing noncardiac surgery were randomly divided into three groups:control group (Group C),high-concentration sevoflurane group (Group S 1) and low-concentration sevoflurane group (Group S2).Etomidate,Propofol,Cisatracurium Besilate and Fentanyl were used for intravenous anesthetic induction and maintenance of anesthesia.In addition,B ispectralindex (BIS) remained between 35 ～ 45 and 45 ～ 55 in groups S1 and S2,re spectively.BIS remained between 40 ～ 50 in group C.Perioperative hemodynamic changes,ECG ST-segment before induction of anesthesia,endotracheal immediate intubation and extubation were recorded.Plasma concentrations of cTnT,high sensitive cardiac troponin (hs-cTnT) and high sensitive ereaetive protein (hs-CRP) were detected with central venous blood before anesthesia induction and immediate extubation.Results Compared with group C,the incidences of hypertension,tachycardia,myocardial ischemia,proiosystole and atrial fibrillation were significantly reduced in groups S1 and S2 (P ＜ 0.05);The incidences of bradycardia and hypotension groups were significantly higher in group S1 (P ＜ 0.05).Compared with group S1,the incidences of hypotension,bradycardia,myocardial ischemia were significantly reduced in group S2 (P ＜ 0.05).Compared with group C,plasma concentrations of cTnT,hs-cTnT and hs-CRP were significantly reduced after endotracheal extubation in group S1 and S2 (P ＜ 0.05).Conclusion Myocardial protective effect is better and less risky for patients with coronary artery disease undergoing noncardiac surgery by inhalation of 1.0％ to 2.5％ sevoflurane to maintain BIS between 45 to 55.