Objective To observe the clinical outcomes of three different nutritional treatments for the postoperative lung cancer with chylothorax patients, and to provide reference for future clinical treatment. Methods According to the inclusion and exclusion criteria, 45 patients were randomly divided into 3 groups: total parenteral nutrition (TPN) group, medium⁃chain triglyceride (MCT) diet group and low⁃fat (LF) diet group, with 15 patients in each group. After diagnosis of chylothorax, the patient immediately received nutritional treatment. Results Albumin levels of patients in the three groups were significantly lower at the time of diagnosis of chylothorax than at the time of admission (P<0.05). After nutritional treatment, albumin levels of patients in the three groups were significantly higher at the time of discharge than at the time of diagnosis, and the difference was statistically significant (P<0.05). The subjective comfort scores after 7 days nutritional treatment of the three groups were lower than that at the time of diagnosis of chylothorax (P<0.05), and the subjective comfort score of the TPN group was highest, followed by the LF group and TPN group in turn, with obvious difference between mutual groups (P<0.05). The amount of chest drainage after 7 days of nutritional treatment, the time to removal of drainage tube and ligation rate were no significant in the three groups (P>0.05).But the cost of nutritional treatment and the length of hospital stay after diagnosis in the MCT group and LF group were significantly lower than those in the TPN group (P<0.05). Conclusion The diet supplemented with MCT should be the first choice of nutritional treatment for the postoperative lung cancer with chylothorax patients.