Coronary heart disease often causes angina pectoris, at this time the left shoulder pain is a kind of involving pain caused by angina attack. The site of angina pectoris is mainly behind the sternal body, may spread to the precordial area, about the size of the palm range, or may be across the chest, the boundary is not clear. It often radiates to the left shoulder, the inside of the left arm up to the ring and little fingers, or to the neck, throat, and jaw. Enthesopathy is the occurrence of pain or nociceptive hypersensitivity at a distant body site caused by certain visceral diseases, often at a body site that has the same embryonic segmental and dermatomal origin as the affected viscera. The heart and upper arm originate at the same segmental level, so in coronary myocardial ischemia, pain often radiates to the left shoulder and left upper arm. The mechanism of referred pain involves the convergence and projection of nociceptive nerve fibers and is a complex physiological phenomenon. However, it is this performance characteristic of referred pain that provides ideas for the diagnosis of some diseases. For example, when the left shoulder pain, it is necessary to consider not only is caused by simple shoulder disease, but also necessary to consider whether there is the possibility of coronary heart disease. Therefore, shoulder pain should be taken seriously and prompt medical attention should be sought.