Pain under the left chest should be alert to heart disease, intercostal neuralgia, pleural disease, trauma and so on. 1. Heart disease: such as coronary heart disease, coronary artery lumen narrowing or occlusion, mostly manifested as chest pain, chest tightness, chest tightness, etc., fatigue or emotional excitement easily triggered. 2. Intercostal neuralgia: mostly manifested as strip pain along the distribution of intercostal nerves, needle-like or burning pain. 3. Pleural diseases: such as tuberculous pleurisy, chest pain, chest tightness and other symptoms, can also be accompanied by low fever, night sweats and other systemic symptoms. 4. Trauma: local soft tissue injury or rib fracture caused by impact or extrusion, which can be manifested as chest pain, chest tightness, etc., and the pain can be aggravated by coughing or position change, and localized skin lesions or bruises can be seen. Pain under the left chest can also be seen in other diseases, it is recommended that patients go to the hospital in a timely manner, so as not to delay the condition.