Chronic obstructive pulmonary disease (COPD) is a chronic disease of the respiratory system. The key issue in determining whether such patients can undergo surgery is the incidence of complications, especially fatal complications, after the patient’s surgery. Generally speaking, the incidence of postoperative complications in COPD patients is related to the severity of COPD and the type of complications that occur. The site of surgery is an important influencing factor, with chest surgery and upper abdominal surgery being the most dangerous. For COPD, preoperative surgical risk assessment is extremely important. The assessment is based on medical history, physical examination, chest X-ray and pulmonary function, among which pulmonary function test is more important, especially for COPD patients who want to undergo lung resection. Pulmonary function tests generally include: resting lung volume, diffusion function, diastolic test, and arterial blood gas analysis at rest. Overall, it is believed that the incidence of respiratory failure after pneumonectomy is higher in patients with preoperative FEV1 <2L or <50% of the expected value, and/or DLCO <50%.