Epilepsy is a kind of common neurological diseases in the world. Over 50% of epilepsies have genetic basis. We define "idiopathic epilepsy" as a kind of epilepsy or epilepsy syndrome only with genetic factors, and idiopathic generalized epilepsies (IGEs) is a major type of idiopathic epilepsies. Susceptibility genes of epilepsies are mainly ion channel genes. Both gene mutation and copy number variation lead to epilepsies. Childhood absence epilepsy (CAE) is a crucial part of IGEs. Due to the consistency of CAE's phenotype and results of EEG, studies related to CAE susceptibility genes tend to be easier to conduct. Through these studies about IGEs /CAE susceptibility genes, we can determine pathogenic model of epilepsy genetics, and find the way to diagnose accurately in molecular genetics, to identify types of epilepsies, to detect targets of antiepileptic drugs, and provide a basis for gene therapy.