【Abstract】 Objective To investigate the effect of dexmedetomidine on analgesic morphine and immune function in patients after radical resection of lung cancer. Methods Eightyfour patients underwent elective radical resection of lung cancer (grade ASA I ~ II) in August 2013August 2015 were selected as study subjects. According to the random number table, they were divided into dexmedetomidine group and control group, 42 cases in each. Dexmedetomidine group was infused with dexmedetomidine at 005μg/kg·min1 when anesthesia induction, 10 min later. The dose was maintained at 04μg/kg·h1 till the end of operation. The control group was infused with the same dose of normal saline during operation. The postoperative spontaneous breathing recovery time, extubation time and adverse reactions during analgesia were statistically analyzed. At postoperative 12h and 13 ~ 24h, the doses of morphine and the times of effective PCA at postoperative 48h were recorded. At postoperative 4h, 12h, 24h and 48 h, visual analogue scale (VAS) was issued to evaluate the pain degree in patients. Before anesthesia induction (T0), on extubation (T1), at postoperative 24h (T2) and 48h (T3), T cells in peripheral blood were detected. Results The postoperative spontaneous breathing recovery time and extubation time of dexmedetomidine group were shorter than those of the control group (P < 005). At postoperative 12h, 13 ~ 24h and 48h, the times of effective PCA in dexmedetomidine group was less than that in the control group (P < 005); Compared with that at postoperative 4h, the VAS scores of the two groups at postoperative 12h, 24h and 48h were significantly lower (P < 005). The VAS scores of the observation group at postoperative 12h, 24h and 48h were lower than those of the control group (P < 005). Compared with those at T0, CD4+ and CD4+/CD8+ at T1, T2 and T3 were lower (P < 005), while there was no obvious change of CD8+ (P > 005). CD4+ and CD4+/CD8+ in dexmedetomidine group at T1, T2 and T3 were higher than those in control group at different time points (P < 005). The incidence of adverse reactions in dexmedetomidine group during analgesia (1667%) was significantly lower than that in the control group (3810%) (P < 005). Conclusion The application of dexmedetomidine in perioperative period can reduce perioperative immunosuppression and reduce postoperative morphine dose in patients undergoing radical resection of lung cancer.