Male left-sided chest pain can be divided into three cases: First, if chest pain appears suddenly, pneumothorax or angina should be considered, pneumothorax is manifested as stabbing pain in the chest and progressive dyspnea, mostly with a clear history of trauma or a history of severe cough, while angina is manifested as pressure pain in the anterior thoracic region, mostly combined with posterior back radiating pain, often triggered by emotional excitement. Secondly, if the pain is chronic, lung cancer or neurological disorders are considered. Lung cancer is manifested as vague pain in the chest with irritating cough or hemoptysis, while neurological disorders mostly have pain distributed along the rib edge, and the pain can be aggravated after exertion or cold. Thirdly, intermittent pain is considered to be gastroduodenal ulcer or reflux esophagitis, which is manifested as burning pain behind the sternum and accompanied by gastrointestinal symptoms such as acid reflux and belching, and gastroscopy can often make a clear diagnosis.