Abstract： Objective： To observe the effect of Shenmai Injection on postoperative cognitive dysfunction (POCD) and levels of neuron- specific enolase (NSE) in serum in patients with lung cancer. Methods： A total of 80 cases of patients with lung cancer were selected as the study subjects， and randomly divided into the study group and the control group，with 40 cases in each group. After anesthesia induction， the study group was treated with intravenous infusion of Shenmai Injection， and the control group was treated with intravenous infusion of glucose solution. The scores of the Self-rating Anxiety Scale (SAS)， Mini- Mental State Examination (MMSE)， Self- rating Depression Scale (SDS) before and after surgery，as well as the incidence of POCD，and levels of NSE and C-reactive protein (CRP) in serum，and the incidence of adverse reactions were compared between the two groups. Results： There was no significant difference being found in the comparison of MMSE scores between the two groups one day before surgery (P＞0.05). On the first，third，and seventh day after surgery，the MMSE scores in the two groups were decreased when compared with those at the first day before surgery (P＜0.05)，and showed an upward trend (P＜0.05)； the MMSE scores in the study group were higher than those in the control group at the same time point (P＜0.05). On the first day before surgery，there was no significant difference being found in the comparison of scores of SAS and SDS between the two groups (P＞0.05)；on the first， third，and seventh day after surgery，the scores of SAS and SDS in the two groups were increased when compared with those on the first day before surgery (P＜0.05)，and showed an upward trend (P＜0.05). At the same time point，the scores of SAS and SDS in the study group were lower than those in the control group (P＜0.05). There was no significant difference being found in the comparison of incidence of POCD between the two groups one day after surgery (P＞0.05). On the third and seventh day after surgery，the incidence of POCD in the two groups were decreased when compared with those on the first day after surgery (P＜0.05)， and showed a downward trend (P＜0.05)； the incidence of POCD in the study group was lower than that in the control group at the same time point (P＜0.05). On the first day before surgery， there was no significant difference being found in the comparison of levels of NSE and CRP in serum between the two groups (P＞0.05). On the first and third day after surgery，the levels of NSE and CRP in serum in the two groups were increased when compared with those on the first day before surgery (P＜ 0.05)，and showed a trend of first increasing and then decreasing (P＜0.05)；the levels of NSE and CRP in serum in the study group were lower than those in the control group at the same time point (P＜0.05). The incidence of adverse reactions was 2.50% in the study group，and 5.00% in the control group，there being no significant difference (P＞0.05). Conclusion：Shenmai Injection can effectively improve POCD in patients with lung cancer， enhance cognitive ability， reduce inflammation levels， and alleviate anxiety and depression.