Lung ultrasound (LUS) is a safe and feasible bedside imaging method, which is increasingly applied in the diagnosis of lung diseases. Rapid and accurate evaluation of perioperative atelectasis occurrence is very important because it is closely related to hypoxemia and postoperative pulmonary complications. LUS is non‑invasive, non‑radioactive and easy to use method for dynamic observation and tracking of patients' lesions. It can be used for perioperative detection and diagnosis of atelectasis. This paper mainly describes the application of LUS in perioperative atelectasis detection and the method of LUS to evaluate atelectasis. As an effective method to evaluate atelectasis, LUS helps to timely adjust ventilation strategies, optimize mechanical ventilation parameters, avoid the occurrence of hypoxemia, and assist anesthesiologists in the diagnosis and treatment of hypoxemia.