Normal human body has only one sternum, the left side of the sternum is higher than the right side, which means that the left side of the ribs on both sides of the sternum should be higher than the right side, mostly due to physiological, rib fracture, pleural effusion and spinal diseases. 1. Physiological reasons: normal human left side of the rib cage and the right side of the rib cage is not completely symmetrical, there will be a side of the protruding performance, no other combined symptoms appear, belong to the normal physiological performance, generally do not need treatment. 2. Rib fracture: one side will be higher than the other after acute rib fracture, and if it is old rib fracture, the broken ends are not aligned neatly, which will also lead to one side being higher than the other. 3. Pleural effusion: If the inflammation of the left side of the lung causes pleural effusion, when the amount of effusion is large, it will be manifested as the fullness of the rib space, and the thorax will be more prominent, and the left side of the sternum will look higher than the right side. 4. Spinal disease: long-term poor sitting and standing posture will lead to different degrees of scoliosis, which will also affect the height of the rib cage. The left side of the sternum is higher than the right side of the chest bone can also be seen in other diseases, it is recommended that patients seek medical treatment in time, so as to avoid delaying the condition.