【Abstract】 Objective To analyze the value of serum soluble trigger receptor-1 (sTREM-1) level and C-reactive protein/albumin (CRP/Alb) ratio in early diagnosis of pulmonary infection in patients with lung cancer after operation. Methods From June 2017 to September 2018, 105 patients with lung cancer underwent surgical treatment in our hospital were selected as the research objects. According to whether the patients had pulmonary infection or not, they were divided into non-infected lung cancer group (93 cases) and noninfected lung cancer group (12 cases). At the same time, 55 healthy people were selected as the control group during the same period. Levels of serum sTREM-1, CRP and Alb were detected by enzyme-linked immunosorbent assay (ELISA), and the CRP/Alb ratio was calculated. The values of sTREM-1 and CRP/Alb ratio in early diagnosis of post-operative infection of lung cancer were evaluated by drawing ROC. The risk factors of pulmonary infection in patients with lung cancer after operation were analyzed. Results Compared with the control group and the non-infected lung cancer group, the levels of serum sTREM-1, CRP and CRP/Alb in the infected group increased significantly (P＜0.05), while the level of Alb decreased significantly(P＜0.05). ROC curve showed that the areas under curve (AUC) of sTREM1 and CRP/Alb levels predicting pulmonary infection after lung cancer surgery were 0.788 (sensitivity and specificity were 81.8% and 75.8%) and 0.879 (sensitivity and specificity were 90.9% and 78.9%), respectively. Logistic regression analysis showed that anemia, diabetes mellitus, cardiovascular and cerebrovascular diseases and smoking were independent risk factors for pulmonary infection after lung cancer surgery(P＜0.05). Conclusion The levels of sTREM-1 and CRP/Alb are high in patients with post-operative infection of lung cancer, and both of them have high values in early diagnosis of post-operative infection of lung cancer, which are risk factors for pulmonary infection after lung cancer surgery.