The precise location of the epileptic focus is the key to a good treatment outcome of surgery. There is no single method that can simply locate the epileptic focus, and a variety of means should be used for comprehensive localization according to the specific situation of different patients. Level 1: CT or MRI and routine EEG. If CT or MRI reveals a lesion and EEG confirms that the seizure is related to the lesion, for example, EEG when not seizing reveals a significant local epileptiform discharge, or seizure discharges originate in a fixed area that matches the clinical symptoms, the location of the seizure focus can be roughly localized. 50%-60% of patients can be operated directly on this basis, and further use of cortical EEG, which means that electrodes are placed directly on the surface of the brain for recording, to further determine the extent of the epileptic focus. Level 2: If CT or MRI cannot detect the foci, or if the foci detected are not consistent with the EEG examination and clinical seizure manifestations, other ancillary examinations should be performed, for example, examination of isotopes such as positron tomography, and sometimes, depending on the situation, magnetic resonance spectroscopy, which can assist in helping to locate the foci. Then we have to perform invasive examinations that are invasive in nature. Level 3: If all of the above tests are still unsuccessful, the patient should undergo intracranial electrode EEG, which means that the electrodes are placed on the surface of the brain or fixed by sutures in the operating room, and the patient continues to undergo intracranial electrode EEG after returning to the ward, usually for several days, and the EEG is recorded for several seizures. The results are used to localize the epileptic focus.