Neuronal nitric oxide synthase(nNOS)is a recently known key regulatory enzyme in the nervous system,which is closely related to a variety of brain functional disorders.The balance of nNOS activity plays an important role in the occurrence and development of brain functional disorders.Therefore,the intervention of exogenous nNOS can improve some brain functional disorders to a certain extent.Future studies,based on new compounds,will further investigate selective nNOS inhibitors with a view to improving the therapeutic effect of brain functional disorders.This review clarifies the role and latest progress of nNOS in the nervous system.