Left chest pain is caused by irritants from various diseases that act on the nociceptive nerve endings in the organs and tissues of the left chest to produce pain. In addition to chest trauma, left chest pain is also commonly associated with chest wall diseases, cardiac macrovascular diseases, pulmonary diseases, mediastinal diseases and digestive system diseases. 1. Chest trauma resulting in rib fractures and soft tissue contusions can cause left chest pain. 2. Chest wall diseases: left costochondritis, left chest wall bone tumor, left intercostal neuritis, herpes zoster, chest wall tuberculosis and other diseases can cause left chest pain. 3. Cardiac macrovascular diseases: angina pectoris, coronary artery disease, viral myocarditis, cardiac insufficiency, cardiac neurosis, ascending aortic aneurysm, aortic coarctation, descending aortic aneurysm, and other diseases can cause pain in the precordial region of the left chest or pain in the back. 4. Lung diseases: such as pleurisy, pleural mesothelioma, lung infection, pneumothorax, lung cancer and other lung diseases can also cause left chest pain. 5. Mediastinal diseases: mediastinal emphysema, thymoma, posterior mediastinal tumor, esophageal cancer and other lesions can cause anterior chest or back pain. 6. Diseases of digestive system: such as reflux esophagitis, chronic gastritis, gastric ulcer and other diseases can cause left chest pain under the raphe. It is recommended to go to the hospital for diagnosis and treatment of left chest pain in time so as to avoid delaying the condition.