Thumping sound when pressing the left side of the ribs may be related to rib fracture, rib cartilage fracture, costal fasciitis, costochondritis and so on. 1. Rib fracture: when the left side of the rib cage is hit by external force, the rib cage may be fractured, and the fracture site is active, so it may make a thumping sound when pressing the relevant part. 2. Rib cartilage fracture: when the left side of the ribs by violent impact, may also be the left side of the rib cartilage fracture, because the rib cartilage has a certain degree of elasticity, after the fracture is in a relatively large degree of activity in the state, and therefore the local elasticity of the characteristics of the press will be manifested as a thumping and thumping sound. 3. Costal fasciitis: due to long time keep a posture, lack of activity, cause local fascia tension, so as to form edematous or painful nodules, which can be manifested as thumping sound when pressing the left side. 4. Costal chondritis: due to infection, trauma and other factors, resulting in inflammatory reaction of the cartilage at the junction of the ribs and sternum, mainly manifested as obvious pain symptoms in the anterior chest wall, often accompanied by the feeling of swelling, pressure or activities can make the pain symptoms worse, and can also emit a thumping sound. Pressing the left side of the rib cage thumping sound may also have other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, give targeted treatment or treatment.