Objective To evaluate the effectiveness of protective intravenous infusion of magnesium sulfate in perioperation on postoperative atrial fibrillation (POAF) after the lobectomy. Methods The method of matching the preoperative age and risk factors of POAF was adopted and 103 patients who underwent a scheduled lobectomy were divided into the magnesium sulfate group (n=49) and control group (n=54) according to whether magnesium sulfate was infused. Patients of the magnesium sulfate group were infused with 25% magnesium sulfate of 2.5 g/d for 3 d before and after surgery. The primary end point to be observed was the incidence of POAF and the secondary end point to be observed was the incidence of side effects and other complications. Results The differences of clinical data of two groups were not statistically significant. The incidence of POAF of the magnesium sulfate group was lower than that of the control group (6.1% vs 22.2%, P=0.026). The incidences of supraventricular tachycardia and ventricular premature beat of the magnesium sulfate group were also lower than those of the control group, but the differences were not statistically significant. The differences of other complications of two groups were not statistically significant. Conclusion Intravenous infusion of magnesium sulfate in perioperation can reduce the incidence of POAF. More randomized controlled studies are needed for further verification and clinical application.