Objectives: To study the relationship between EEG features of secondary epilepsy after craniocerebral operation.Methods: The EEGs and clinical deta were analyzed retrospectively in 54 patients eith seizures after craniocerebral operation. Results: EEGs are normal in six patients and abnormal in 48 ones (with an abnormality rate of 89%), in which 44 showed local abnormality and four showed widespread abnormality . In local abnormal EEGs, abnormality showing unilateral slow wave are noted in 13 patients and regional slow wave in 31 ones (three of which showed regional epileptiform discharges). In widespread abnormal EEGs, mild abnomality ware noted in two patients, moderate and severe abnormality in only one patient respectively. Conclusions: The local abnormality rate of EEGs in patients with secondary epiliepsy after craniocerebral operation is 92% in the total abnormality, in which the rate of local epileptiform discharges is 4%. The local slow waves are related to the preoperative focus, the operation site and the secondary focus after operation.[ Objectives: To study the relationship between EEG features of secondary epilepsy after craniocerebral operation. Methods: The EEGs and clinical deta was analyzed retrospectively in 54 patients eith seizures after craniocerebral operation. Results: EEGs are normal in six patients and abnormal in 48 ones (with an abnormality rate of 89%), in which 44 showed local abnormality and four caused substantial abnormality. In local abnormal EEGs, abnormality showed unilateral slow waves are noted in 13 patients and regional slow wave in 31 ones (three of which showed regional epileptiform discharges Conclusions: The local abnormality rate of EEGs in patients with secondary epiliepsy after craniocerebral operation is 92% in the total abnormality, in which the rate of local epileptiform discharges is 4%. The local slow waves are related to the preoperative f ocus, the operation site and the secondary focus after operation. [