Objective To summarize the clinical phenotype and gene mutation characteristics of early epileptic encephalopathy caused by STXBP1 gene mutation and the application of second-generation gene sequencing in etiological diagnosis.Methods Retrospective analysis of clinical characteristics,gene test results,treatment and efficacy of 19 children with epileptic encephalopathy with genetic diagnosis of STXBP1 gene mutation who were seen in the Department of Pediatrics of the Second Hospital of Zhejiang University School of Medicine from January 2017 to January 2021.Results The disease started within 1 month after birth in 15 children(78.9%).All 19 children had significant electro-encephalo gram(EEG)changes:13 cases of burst suppression(68.4%)and high arrhythmia in 12 cases(63.2%).A total of 18 pathogenic variants were detected in 19 children,all of them new,of which 7 loci have not been reported so far.Five children were diagnosed with Otahara syndrome,five with infantile spasms,and nine with an epileptic syndrome that could not be classified.At a follow-up of 6 months to 4 years and 5 months,1 case was discontinued,5 cases had complete remission of seizures,6 cases had partial remission,and 7 cases were ineffective.8 of the 12 children with seizure remission or control were treated effectively with combination levetiracetam,4 of the 6 children with spasms responded with the addition of vigabatrin,and 7 presented with drug refractory epilepsy.All 19 children had varying degrees of developmental delay.Conclusion Mental-motor retardation and recurrent seizures are the main,independent phenotypic features of STXBP1-encephalopathy,STXBP1 gene variants are predominantly de novo variants,second-generation gene sequencing diagnosis helps in the early diagnosis of STXBP1-encephalopathy,levetiracetam and aminocaproic acid may be partially effective in controlling seizures in STXBP1-encephalopathy,and ketogenic diet provides new ideas for early-onset epileptic encephalopathy treatment provides a new idea.