Objective:To explore the differential diagnosis and different treatment methods of chylothorax and pseudochylothorax after lung cancer surgery.Methods:Clinical data of 1 584 surgical patients with non-small cell lung cancer from January 2016 to December 2021 were analyzed, 21 cases of chylothorax and 8 cases of pseudochylothorax were identified and analyzed to compare the differences in pleural fluid chyle test, pleural effusion biochemical values, total cholesterol, triglycerides, total cholesterol/triglyceride ratio, leukocyte count, bacterial culture and treatment.Results:The incidence of chylothorax after lung cancer surgery was 1.3%, and the incidence of pseudochylothorax was 0.5%; 80.9%% of chylothorax on the right side was significantly higher than 19.1% of chylothorax on the left side, and the difference was statistically significant( P<0.05). Pseudochylothorax occurred on the right side(100%). The difference between chylothorax and pseudochylothorax in pleural fluid tests for cholesterol and triglyceride was statistically significant( P<0.05), the leukocyte count was significantly higher in pseudochylothorax than chylothorax, and the difference was statistically significant( P<0.05). The differences in drainage before treatment, postoperative drainage time and postoperative hospitalization time between the two groups were statistically significant( P<0.05). The success rate was 61.9% in 13 cases of chylothorax treated conservatively and 38.1% in 8 cases of thoracic duct clamping; all cases of pseudochylothorax were treated conservatively with a success rate of 100%. Conclusion:In naddition to pleural fluid chyle test and pleural effusion biochemical values, total cholesterol, triglyceride and total cholesterol to triglyceride ratio in pleural fluid should be tested to identify chylothorax and pseudochylothorax, high triglyceride in pleural fluid diagnosed as chylothorax; Pseudochylothorax is diagnosed with a cholesterol/triglyceride ratio >1 in the pleural fluid, pseudochylothorax is usually treated conservatively. Chylothorax is treated conservatively and surgically according to different conditions. If the drainage flow is greater than 800 ml/day for 3 consecutive days or if it causes serious electrolyte disorders, it is recommended to perform thoracoscopic-assisted thoracic duct clamping via right-sided approach.