ObjectiveTo compare the postoperative chylothorax outcomes of robot-assisted thoracic surgery (RATS) and video-assisted thoracoscopic surgery (VATS), analyze the risk factors for postoperative chylothorax after minimally invasive radical lung cancer resection and explore possible prevention and control measures. MethodsBetween June 2012 and September 2020, 1083 patients underwent minimally invasive pulmonary lobectomy and systematic lymph node dissection in our hospital, including 578 males and 505 females with an average age of 60.6±9.4 years. Patients were divided into two groups according to the operation methods: a RATS group (499 patients) and a VATS group (584 patients). After propensity score matching, 434 patients were included in each group (868 patients in total). Chylothorax and other perioperative indicators were compared between the two groups. Univariate and multivariate logistic regression analyses were performed to identify risk factors for postoperative chylothorax. ResultsOverall, 24 patients were diagnosed with chylothorax after surgery. Compared with the VATS group, the rate of chylothorax was higher (3.9% vs. 1.6%, P=0.038), the groups and numbers of dissected lymph nodes were more (both P<0.001), and the intraoperative blood loss was significantly less (P<0.001) in the RATS group. There was no statistical difference in the postoperative hospital stay (P=0.256) or chest tube drainage time (P=0.504) between the two groups. Univariate analysis showed that gender (P=0.021), operation approach (P=0.045), smoking (P=0.001) and the groups of dissected lymph nodes (P<0.001) were significantly associated with the development of chylothorax. Multivariate analysis showed that smoking [OR=4.344, 95%CI (1.149, 16.417), P=0.030] and the groups of dissected lymph nodes [OR=1.680, 95%CI (1.221, 2.311), P=0.001] were the independent risk factors for postoperative chylothorax. ConclusionCompared with the VATS, the rate of chylothorax after RATS is higher with more dissected lymph nodes and less blood loss. The incidence of chylothorax after minimally invasive radical lung cancer resection is higher in the patients with increased dissected lymph node groups and smoking history.