Objective　To investigate the genetic variation of early epileptic encephalopathy. Method　The clinical data and gene detection results of early epileptic encephalopathy in a child were analyzed retrospectively. Results　A girl suffered from intermittent and frequent convulsions 30 minutes after birth. Many kinds of antiepileptic drugs, such as phenobarbital, chloral hydrate, diazepam, valproate, levetiracetam, clonazepam, oxcarbazepine were ineffective. Second-generation sequencing revealed a heterozygous mutation of c.1120A>G in KCNA2 gene in the child, which was not carried by either parent and was a new mutation. Conclusion　The pathogenicity of the mutation has been reported in literature, but it is the first report in China. The gene mutation spectrum of early epileptic encephalopathy in China has been expanded.