【Abstract】 Objective To explore the change of cerebrospinal fluid and serum glial fibrillary acidic protein （GFAP） of children with viral encephalitis in acute phase and it's clinical significance. Methods The levels of cerebrospinal fluid and serum GFAP of 38 children with viral encephalitis and 30 lumbar anesthesia children without central nervous system diseases were measured by double antibody sandwich ELISA method. Differences in the levels of cerebrospinal fluid and serum GFAP between the case group and the control group, patients with and without sequelae, and those among patients with different severity were compared, respectively. Results GFAP levels of cerebrospinal fluid in the case group and control group were 1767±1132μg/L and 0234±0091μg/Ｌ（P<001）. Serum GFAP levels in the case group and control group were 0489±0239μg/Ｌand 0197±0070 μg/Ｌ（P<001）. Compared with the control group, the cerebrospinal fluid GFAP in the case group was higher(Ｐ<001). The cerebrospinal fluid GFAP in the severe group was higher than that in the moderate group, also it was higher in the moderate group than that in the mild group（P<001）. The serum GFAP in the severe group was higher than that in the moderate group, but there was no difference in serum GFAP between the moderate group and the mild group（P>005）. The cerebrospinal fluid and serum GFAP levels of children with sequelae were higher than those without sequelae（P<001）. Conclusion The erebrospinal fluid and serum GFAP levels of children with viral encephalitis in acute phase relates to degree of severity increases. Detection of GFAP of children with viral encephalitis contributes not only to assessing the severe degree but also to predicting their prognoses.