To explore the factors affecting the intraoperative conversion of video-assisted thoracoscopic surgery (VATS) to thoracotomy in patients with lung cancer.The clinical data of 80 patients with lung cancer in The Fourth Hospital of Hebei Medical University from May 2019 to December 2021 were retrospectively analyzed. The patients who were treated with VATS alone were included into thoracoscopy group (n= 40), and those who were intraoperatively converted from VATS to thoracotomy were included into conversion group (n= 40). The medical record data were collected, the influencing factors of intraoperative conversion from VATS to thoracotomy were analyzed, and the surgical indexes and postoperative complications were compared between the two groups.Multivariate regression model showed that tumor in the upper lobe, central lung cancer, history of pulmonary tuberculosis, pleural adhesion ≥ Grade-4 and maximum tumor diameter ≥ 35 mm were risk factors for patients with lung cancer undergoing conversion from VATS to thoracotomy (p< 0.05). In the conversion group, the surgical duration and hospital stay were longer, the intraoperative bleeding volume and thoracic drainage volume were larger, and the total incidence of postoperative complications was higher than those in the thoracoscopy group (p< 0.05).Conversion from VATS to thoracotomy may increase the risk of complications in patients with lung cancer. Tumor in the upper lobe, central lung cancer, history of pulmonary tuberculosis, high degree of pleural adhesion and large tumor diameter are risk factors for conversion from VATS to thoracotomy.Copyright: © Pakistan Journal of Medical Sciences.