Epilepsy is one of the most common neurological disorders, and surgical intervention is usually used for drug-resistant focal epilepsy. Cortical electrical stimulation is widely used in preoperative evaluation of epilepsy to explore the anatomical-clinical electrical correlations between epileptogenic and functional networks through electrical stimulation, and the functional brain maps produced by cortical electrical stimulation depict areas of the functional cortex at an individual level, identifying the functional cortex with greater precision, as well as helping to establish epilepsy network, enabling more precise localization of seizure zones and providing a more accurate localization for surgical resection. Electrical cortical stimulation has become a standard technique for the preoperative assessment of brain region function in brain surgery. It is an indispensable part of preoperative evaluation.The main types of functional mapping by electrical stimulation include stereoelectroencephalography (SEEG) and subdural electrode (SDE), SEEG-guided cortical electrical stimulation is gradually becoming more mainstream compared to subdural electrodes, and is increasingly valuable and important as a preoperative evaluation of epilepsy. It is increasingly demonstrating its value and importance because it avoids craniotomy, takes less time for surgery, has fewer associated complications and infections, and can explore deep lesions, increasing the understanding of human functional neuroanatomy and enabling more precise localization of seizure zones.This article reviews the history of the development of cortical electrical stimulation technology, the intrinsic mechanisms, the value of the application of SEEG, and also provides a comprehensive comparison between SEEG and SDE, despite the irreplaceable advantages of SEEG, attention should be paid to the unresolved clinical and scientific issues of SEEG, and the establishment of a consensus-based clinical guideline, as the application of this technology will be more widely used in both clinical and scientific work.