A pulmonary aneurysm is an abnormal verrucous dilatation on the pulmonary artery, usually due to atherosclerosis, trauma, and other factors. Pulmonary artery will be aneurysmal expansion, because of the formation of various reasons, manifested as the wall of the pulmonary artery protrudes outward, compression or erosion of neighboring tissues. 1. Atherosclerosis: Smoking, drinking, obesity, staying up late for a long time, and risk factors such as three highs can all cause pulmonary arteriosclerosis. Pulmonary artery aneurysm will produce pressure on the surrounding tissues and organs, such as compressing the trachea, esophagus, laryngeal nerve, etc. Moreover, if the pulmonary artery aneurysm ruptures, it will cause hemorrhage. 2. Trauma: mostly caused by bruising or edema after injury. Trauma leads to arterial injury and blood forms hematoma in blood vessels and soft tissues, resulting in pulmonary aneurysm. If you suffer from pulmonary aneurysm, you must go to the hospital to receive timely treatment accompanied by your family members, so as not to affect the patient’s life and quality of life.