Spasticity can be caused by central nervous system dysfunction, such as cerebral palsy and stroke. The accepted pathogenesis of spasticity is that the muscles are in the state of uninhibited stretch reflex without enough control of central nervous system. So far, there is no ideal way about how to repair central nervous system. However, the uninhibited stretch reflex can be reduced, targeting the posterior root of the spinal cord and peripheral nerves innervating the limbs, which are called selective posterior rhizotomy (SPR) and selective peripheral neurotomy (SPN), respectively. SPN is indicated for focal or multifocal spasticity, which is well accepted due to its low invasiveness and ease of use. How does the operation work? What do we do before and during this operation? Is there any risk to the patients? Our review summarizes the mechanism, indications, preoperative assessments, techniques, and complications of SPN. We hope that the spastic patients, such as pediatric cerebral palsy patients and older stroke patients, will benefit from this surgery.