Objective　To explore the value of active electroencephalography (AEEG) in the diagnosis of  attention-deficit hyperactivity disorder. Methods　Routine EEGs were performed in 179 patients with attention-deficit hyperactivity disorder. AEEGs were performed in 117 patients who have been performed routine EEGs. Results　Abnormal discharge was observed in 17 cases in routine EEGs and epileptiform activities were found in 6 patients. The abnormal rate is 9.5%. Abnormal discharge was observed in 21 cases in AEEGs and epileptiform activities were found in 12 patients. The abnormal rate is 17.9%. Conclusions 　AEEG is an important clinical examination which also serves as a reference for brain function and epilepsy. AEEG could help judge the prognosis of epilepsy comorbiding with attention-deficit hyperactivity disorder.