External trigeminal nerve stimulation (eTNS) is a new non-invasive physical and electrical stimulation therapy based on the anatomical characteristics of the trigeminal nerve. It can control seizures by regulating epilepsia-related brainstem nuclei and part of forebrain structures, regulating neuroinflammation, improving synaptic plasticity and promoting neurogenesis, which has broad clinical application prospects. It has been approved by the European Union as an adjuvant treatment for drug-resistant epilepsy patients over the age of 9 years old. Therefore, this article mainly reviews the central nervous system regulatory mechanism of eTNS in improving epilepsy, eTNS stimulation mode and parameters.