Objective To investigate the difference of clinical manifestation and probe into pathogenic characteristic cerebrospinal fluid in CSF.Methods Medical record of 102 children with acute viral encephalitis were reviewed.And the specfic IgM antibodies of herpes simplex viruses,type 1and type2(HSV-1、HSV-2)、Coxsackie viruses B(CoxBV)、Epstein-Barr virus(EBV)、CMV、Colti virus were determined by PCR in the CSF in some of 102 viral encephalitis cases.Results The HSV encephalitis is dangerous very much.It can cause the obstruction of consciousness(69.2%) and cause to death.Conclusion ①virual encephalitis is the first in the intracranical infection.②The state of HSV viral encephalitis were dangerous than other viral encephalitis.③Colti viral encephalitis is a new pathogeny in children's viral encephalitis on summer.