Pain below the left rib cage may be due to trauma, inflammation or tumor below the rib cage, which is common in chest wall, respiratory system, cardiovascular system and digestive system and other diseases. 1. Chest wall diseases: left rib fracture, left intercostal neuralgia, left chest wall costochondritis, left chest muscle spasm, rib tumors and other chest wall diseases can cause pain below the left rib cage. 2. Respiratory diseases: left lung infection, left pleurisy, left pneumothorax, pulmonary embolism, lung malignant tumor and other diseases can also cause pain under the left rib cage, often accompanied by coughing, coughing up sputum, chest tightness, dyspnea, fever and other symptoms. 3. Cardiovascular diseases: coronary heart disease, angina pectoris, myocarditis, pericarditis and other diseases will cause patients to appear in the left side of the ribs at the bottom of the pain, the pain is generally more intense, often with the onset of triggers, accompanied by chest tightness, palpitations and other symptoms, the risk of such diseases is greater, and need to be vigilant. 4. Digestive system diseases: esophagitis, gastritis, gastric ulcer, pancreatitis and other diseases in some patients, due to the involvement of pain can appear on the left side of the ribs under the pain. Pain under the left side of the rib cage, it is recommended to go to the hospital for further consultation and treatment to clarify the cause of the disease, so as not to delay the condition.