In recent years, an increasing number of pulmonary nodules have been detected through CT screening. The traditional surgical method for lung cancer is lobectomy combined with lymph node dissection. However, recent studies have demonstrated that sublobar resection for early non-small cell lung cancer (NSCLC) is an effective alternative with the additional benefit of preserving more pulmonary function. However, it also faces many problems, the most prominent of which is the rapid and accurate identification of the intersegmental plane (ISP) during surgery. The modified inflation-deflation method for identifying the ISP is the most commonly used method in anatomical sublobar resection. Nevertheless, the lengthy waiting periods and the lack of clear delineation represent significant challenges in clinical practice. The Partial pressure of Oxygen Control method facilitates the efficient determination of the ISP by reducing the oxygen inhalation concentration and ventilator ventilation time during surgery. This results in a reduced PaO2 in arterial blood, thereby accelerating the rapid appearance of the ISP. Thus, the investigators conducted a prospective, randomized, controlled trial to ascertain whether the oxygen partial pressure control method affects the occurrence time of the ISP and PaO2 during one-lung ventilation, in comparison to the modified inflation-deflation method. Furthermore, the objective was to confirm the safety and efficacy of Partial pressure of Oxygen Control method.