Abstract: Objective  To evaluate the clinical effect of Cox-maze Ⅲprocedure in the treatment of cardiac valvular disease with atrial fibrillation. 
Methods  The clinical data of 12 patients with cardiac valvular disease complicated with atrial fibrillation undergoing Cox-maze Ⅲ  procedure were retrospectively analyzed. All patients underwent Cox-maze Ⅲprocedure and cardiac valve replacement through median sternal incision under general anesthesia. Cardiac function was observed by echocardiography before and after surgery, and clinical experience was summarized. 
Results  The whole group successfully completed heart valve surgery and maze surgery, without perioperative death, no third-degree atrioventricular block, coronary artery injury and cerebrovascular accident. The extracorporeal circulation time was 143-201 min, with an average(174.43±15.46) min. Aorta occlusion lasted 81-96 min(88.71±3.54) min on average, and ventilator application lasted 18-47 h. There was no atrial fibrillation heart rate when the surgery was repeated. Postoperative perioperative complications: 1 case of low cardiac output syndrome was improved after treatment of strong cardiac diuretic and improved cardiac function. One case of hypoxemia, after infection control, atomization of sputum drainage, strengthening the recovery after body therapy. During the period of hospitalization, 4 patients were treated with pacemaker pacing, 2 with atrial fibrillation, 1 with atrial rhythm, 1 with electro-cardioversion, the rest were treated with supplementary blood volume and antiarrhythmic drugs, and 11 cases (91.67%) recovered sinus rhythm after discharge. All patients were followed up regularly for 3 months to 2 years after surgery, and their cardiac function was significantly improved. With the extension of time, the left atrial diameter(LAD), left ventricular end diastolic dimension(LVEDD), and left ventricular end-systolic diameter(LVESD) were gradually reduced, left ventricular ejection fraction（LVEF） increased gradually, the difference was statistically significant(P＜0.01). 
Conclusion  The clinical effect of Cox-maze Ⅲ procedure in the treatment of valvular heart disease combined with atrial fibrillation is positive, accurate grasp of surgical indications and strict grasp of surgical operation technology is conducive to improve the surgical effect.

Key words: heart valve diseases, atrial fibrillation, Cox-maze Ⅲ procedure