Left hand and shoulder pain may be caused by the following reasons: first, cervical spondylosis, when cervical spondylosis occurs, it can compress the nerve roots and cause pain in one shoulder and hand, which can be accompanied by numbness and weakness, then the X-ray, MRI and CT examination of the cervical spine should be performed for early diagnosis and treatment; second, myofasciitis, when myofasciitis occurs, it can cause pain on the inner side of the scapula, which can be radiated to the ipsilateral Third, head diseases, if there is a tumor in the head, which compresses the nerve, it can also cause pain and weakness in one upper limb, then CT and MRI of the head should be performed for early diagnosis and treatment.