Abstract： Objective To investigate the effect of C8 nerve root division on the treatment of spastic cerebral palsy in the upper limbs. Methods Two patients were treated with division of the C8 never root. Supraclavicular incision was made to expose the C5-T1 nerve roots. The intraoperative electromyographic recording technique was used to monitor the responses from the flexor digitorum and flexor carpi ulnaris muscle groups simultaneously. The C5-T1 nerve roots were stimulated and the evoked muscle amplitude potentials (EMAP) were recorded from the muscle groups. The EMAP of the muscle groups obtained during electrical stimulation of the C8 nerve root was the largest, which was used as the basis for C8 nerve root division.Results Division of the C8 nerve root slightly affected the function of the upper limb, and reduced the muscle tone of the flexor wrist and digitorum.Conclusion Division of the C8 nerve root can reduce the muscle tone of the flexor wrist and digitorum in a short time. The long-term effects need to be followed up further.