Various factors such as surgery and anesthesia can cause perioperative diaphragmatic dysfunction (DD). Diaphragm ultrasound can accurately measure the thickness and excursion of the diaphragm, accurately reflect the changes of diaphragm function during perioperative period, help anesthesiologists to early identify patients with DD and give timely and effective intervention. This article reviews the application of diaphragmatic ultrasound in perioperative anesthesia, focusing on the preoperative assessment of diaphragmatic dysfunction associated with chronic obstructive pulmonary disease (COPD), sepsis and stroke, intraoperative identification of DD caused by brachial plexus block, and postoperative assessment of cardiac function, evaluation of phrenic nerve injury after cardiac, thoracic, and abdominal surgery, as well as guidance of postoperative extubation. Diaphragm ultrasound is a necessary skill for anesthesiologists in the new era, which can help anesthesiologists optimize perioperative anesthesia management and improve the prognosis of patients.