The most common clinical causes of single-limb weakness are central system diseases, including cerebral infarction, cerebral hemorrhage, transient ischemic attack, and acute onset of central demyelinating disease. In addition, peripheral neuropathy can sometimes cause single limb weakness, clinically common cervical spondylosis compression of nerves and upper limb localized nerve compression, the specific causes need to be based on the patient’s symptomatic onset of time speed, duration of time. Sudden onset of persistent, especially with numbness of the limbs of the single limb weakness, need to highly consider acute cerebrovascular disease, should be as early as possible to improve the hospital examination to clarify the diagnosis. If the disease starts slowly, especially if it comes and goes, consider peripheral neuropathy, such as cervical spondylosis, peripheral neuropathy caused by compression of the median nerve, ulnar nerve or radial nerve.