The most important thing in the surgical treatment of epilepsy is the localization of epileptic foci. The current method of epileptic foci localization mainly relies on: 1. Video EEG of the seizure video can clearly grasp the evolution of the patient’s seizure, while the EEG can record the seizure-related EEG origin; 3. Magnetic resonance, MRI can detect the patient’s seizure-related lesions, such as tumor, inflammation, degenerative changes of brain injury. For simpler cases, the above can be done to localize the epileptic foci, but some more complicated cases, such as those where MRI does not find obvious foci, where the scalp EEG seizure origin is not obvious, and where the patient’s seizure symptoms are consistent with the manifestation of partial epilepsy but the origin cannot be pinpointed, or where the patient’s seizures may be close to or overlap with some important brain functional areas, these cases require intracranial Electrode implantation. The purpose of implantation is to pinpoint the origin of the seizure. Because the electrodes of intracranial EEG are directly covered on the surface of the brain and can directly record the abnormal discharge of the brain underneath the electrodes, unlike the scalp EEG, which is attenuated and diffused by the skull and scalp, the EEG signal becomes weaker and the range is enlarged, so that some of the epilepsy origins cannot be detected and some of the scalp EEG locates a large range of epileptic foci, because the brain is not regenerable. The brain should be removed as little as possible, and the brain of epileptic origin should also be cut off, so as to ensure both the efficacy of epilepsy and the brain function is not affected. After the implantation of intracranial electrodes, we monitor the patient’s EEG, including interictal and ictal EEG, which are valuable for localizing the epileptic foci. Even if sometimes the epileptic focus is located in the functional area and postoperative hemiplegia and aphasia cannot be avoided, knowing the location of the epileptic origin and functional brain areas and their relationship can minimize the degree of postoperative brain deficits and provide important guidance for compensatory recovery after brain deficits. The figure below shows an intracranial electrode implantation coverage and localization of epileptic foci and functional areas. The patient’s brain was reconstructed using brainvoiger software after the patient’s own 3T MRI scan, and then the electrodes covered the location of the patient’s possible seizure foci. The yellow area behind is the location of the tongue motor area, and the blue area is the location of the patient’s left orofacial motor area, because the patient appears to slant the corners of the mouth to the right when electrically stimulating these points. Therefore, intracranial electrodes are very important. If there are no intracranial electrodes for localization, the epileptic foci may be more extensive and may remove part of the speech area or the motor area of the tongue or the corners of the mouth in the back, causing the possibility of aphasia and hemiparesis.