This study investigated prognostic evaluation of child patients with viral encephalitis through ambulatory electroencephalogram (AEEG) and regular electroencephalogram (REEG). A total of 94 child patients who were clinically diagnosed with viral encephalitis in Yantaishan Hospital of Yantai from May 2010 to July 2014, was examined with AEEG and REEG, respectively and randomly divided into AEEG group (n=47) and REEG group (n=47). The probabilities of detecting abnormal electroencephalographic activities with two examination methods were compared. The detection rates of abnormal electroencephalographic activities with AEEG and REEG were 80.0 and 65.0%, respectively, with significant differences (P<0.05); the probabilities of detecting epileptiform discharge with AEEG and REEG were 42.5 and 6.3%, respectively, with significant differences (P<0.05). The hospitalization time and time of electroencephalogram (EEG) restoring to normal of child patients with encephalitis in the REEG group were significantly longer than those of child patients with encephalitis in the AEEG group, with statistically significant differences (P<0.05). Among child patients in the AEEG group, the incidence rate of severe illness was 2.1%, and both the incidence rates of clinical recurrence and of sequela were 0. Among child patients in the REEG group, the incidence rate, clinical recurrence rate and incidence rate of sequela were 8.5, 12.7 and 8.5%, respectively, with statistically significant differences (P<0.05). To some extent, the EEG abnormality reflects the disorder degree of brain environment of child patients with viral encephalitis. The treatment effect and prognosis of child patients with viral encephalitis can be clinically evaluated based on EEG monitoring results of child patients, which has a certain clinical guiding significance. AEEG has important significance to the auxiliary diagnosis of viral encephalitis, with higher sensitivity than REEG.