Abstract: Objective To analyze the effect of dexmedetomidine on the protection of lung in lung cancer patients with single lung ventilation. Methods Eighty-two lung cancer patients who received surgical treatment under single lung ventilation anesthesia,and the patients were randomly divided into the control group(n=40) and the observation group(n=42).Before anesthesia induction,the patients in the observation group received intravenous injection of dexmedetomidine hydrochloride with the loading dose of 0.5 μg/kg,and finished infusion within 10 minutes,then received intravenous infusion at 0.25 μg/(kg·h) till 30 minutes before surgery;and the patients in the control group received intravenous infusion of physiological saline solution with the same volume.The number of neutrophils(PMN),serum xanthine oxidase(XOD) and myeloperoxidase(MPO) levels before anesthesia induction(T0),at the moment of single lung ventilation(T1),30 minutes after single lung ventilation(T2),60 minutes after single lung ventilation(T3),30 minutes after lung expansion(T4) and 24 hours after surgery were compared between two groups.The surgical condition and the amount of various narcotic drugs were compared between two groups. Results The PMN,XOD and MPO levels in two groups at T2,T3,T4 and T5 time points were significantly higher than those at T0 time point(P<0.05).The PMN,XOD and MPO levels at T2,T3,T4 and T5 time points in the observation group were significantly lower than those in the control group(P<0.05).There were no significant differences in intraoperative blood loss,24-hour urine output and fluid volume between two groups(P>0.05).The recovery time of the observation group was significantly longer than that of the control group,and the difference was statistically significant(P<0.05).The remifentanil and propofol dosage in the observation group was significantly lower than that in the control group,and the difference was statistically significant(P<0.05).There was no statistically significant difference in cisatracurium dosage(P>0.05). Conclusion Dexmedetomidine can reduce the PMN count and serum XOD,MPO expression level in lung cancer patients with single lung ventilation,which have a positive protective effect on lung tissues.