Seizures, due to abnormal excessive or synchronized activity of neurons in the brain, result in transient symptoms, and recurrent seizures are inherent. Most patients can control their seizures by taking medication, but some patients have ineffective drug control, called refractory epilepsy, and surgery is an important tool for treating refractory epilepsy. The key to surgical treatment is the localization of the lesion, that is, the identification of the abnormally excited neuronal population. The purpose of preoperative evaluation is to identify the epileptogenic foci, and the following assessment tools are commonly used: a. Clinical information on seizures It is extremely important to take a careful history. In particular, the presence or absence of aura before the seizure and the performance of the patient before loss of consciousness can also help to infer the location of the lesion. Second, video EEG and magnetoencephalography Epilepsy is a symptom caused by abnormal neuron function in the brain, so neurophysiological testing is the most reliable evidence of seizure lesion localization. 24-hour or longer video EEG testing has the advantage of capturing the symptoms of the patient’s seizure, as well as the simultaneous recorded EEG changes, which can localize the seizure initiation area and provocation area in two dimensions. It provides important data for the physician’s diagnosis and treatment. Magnetoencephalography records the magnetic field signal of the brain during the interictal period and uses magnetic source imaging to integrate the site of abnormal discharge in the seizure provocation area into the magnetic resonance image, which identifies the lesion to the specific brain gyrus and brain sulcus and realizes three-dimensional localization, facilitating the surgeon’s surgical operation. Magnetic resonance imaging Magnetic resonance greatly improves the range of resolution of possible epileptogenic foci, especially disorders caused by cortical malformations in the pediatric brain, such as abnormal cortical development. Positron emission computed tomography measures the level of glucose metabolism in the brain. Most of the lesions in epilepsy are hypoglycemic in the interictal period, which helps to determine the location of the lesions. V. Intracranial electrode EEG testing 50% of patients can be operated on directly and with more satisfactory results by the above non-invasive evaluation, while other patients require placement of intracranial electrodes. Compared to scalp EEG (where the overall signal is recorded over a 6 cm2 area), intracranial electrode EEG monitoring has the significant advantage of identifying EEG signals over a 1 cm2 area and recording abnormal discharges at an early stage of their appearance, before they have spread widely. Intracranial electrodes avoid signal loss and distortion caused by the influence of the scalp and skull, etc., and also largely avoid interference from various artifacts such as eye movements, electromyography, and movements.