OBJECTIVE：To investigate the postoperative analgesic effect of Dexmedetomidine combined with Remifentanil on patients in lung cancer resection and its effect on immune function. METHODS： 60 lung cancer patients in lung cancer resection were randomly divided into control group （30 cases） and observation group （30 cases）. All patients with endotracheal intubation received lung cancer resection under general anesthesia. After surgery， control group received Remifentanil hydrochloride 10 μg/（kg·d）+Ondansetron hydrochloride injection 16 mg， adding into 0.9％ Sodium chloride injection co-formulated into 100 ml； observation group received Dexmedetomidine hydrochloride injection 0.75 μg/（kg·d）+Remifentanil hydrochloride 10 μg/（kg·d）+Ondansetron hydrochloride injection 16 mg， adding into 0.9％ Sodium chloride injection co-formulated into 100 ml. Background doses in 2 groups were 2 ml/h， self-controlled amount was 2 ml， lockout time was 15 min. Visual analog pain score （VAS）， IFN-γ， IL-10 level， T cell subsets （CD3+，CD4+，CD8+，CD4+/CD8+） after 6，12，24，48 h and the incidence of adverse reactions in 2 groups were observed. RESULTS： VAS scores after 6， 12， 24， 48 h in observation group were significantly lower than control group， and VAS scores after 24， 48 h in 2 groups were significantly lower than that after 6 h， with statistical significance （P＜0.05）. IFN-γ levels after 6， 12， 24， 48 h in observation group were significantly lower than control group， and IFN-γ levels after 12， 24， 48 h in 2 groups were significantly lower than that after 6 h， IL-10 level after 12，24，48 h in observation group were significantly higher than that 6 h and control group， with statistical significance （P＜0.05）. CD3+ after 6， 24， 48 h， CD4+ after 6， 12， 48 h， CD4+/CD8+ after 12， 24， 48 h in observation group were significantly higher than control group， CD8+ after 12， 24 h were significantly lower than control group， CD3+，CD4+ after 12，24，48 h in 2 groups， CD4+/CD8+ in control group， and CD8+ after 12， 24 h in observation group and after 24 h in control group were significantly lower than that after 6 h， with statistical significance （P＜0.05）. There was no significant difference in the incidence of adverse reactions in 2 groups （P＞0.05）. CONCLUSIONS： The postoperative analgesic effect of Dexmedetomidine combined with Remifentanil on patients in lung cancer resection is superior to Remifentanil alone， it can improve the immune function， with good safety.