Rib pain below the left chest may be caused by the following reasons: 1. It may be caused by costochondritis, in the attack of this kind of disease, it may cause the development of the 3rd-5th rib cartilage on the left side, which will lead to the pain in this place. 2. This kind of situation may be caused by the heart-related lesions, for example, in the attack of angina pectoris, myocardial infarction, pericardial effusion, pericardial adhesion or pleural adhesion, it may cause the pressure pain in this place, and it will be aggravated with the patient taking a deep breath. 3. When angina pectoris, pericardial infarction, pericardial effusion, pericardial adhesion or pleural adhesion occurs, it may cause compressive pain in this area, and it will be aggravated with the patient’s deep breathing.3. This situation may be caused by trauma in this area, for example, if this area is hit by direct violence, or there is a situation of long-term compression, it will cause bone contusion, bone fracture or aseptic inflammation, which will lead to the pain. 4. This situation may be caused by Chest wall phlebitis is often caused by cold or previous trauma, which leads to inflammation of the chest wall veins, resulting in pain and causing the patient to think that there is pain around the ribs.