Objective: To investigate the effect of pediatric early warning score(PEWS) on the evaluation of severity of emergency children admitted to pediatric intensive care unit(PICU). Methods: A total of 1 069 cases hospitalized through emergency room into PICU in Guiyang Children′s Hospital, from January to December in 2017 were analyzed, and the PEWS was recorded for the first time in emergency room and PICU, while receiver operating curve was used to analyze the efficacy of PEWS to diagnose the children, who were at risk of clinical deterioration and required transfer to the PICU, which included the sensitivity, specificity, Youden index.The diagnostic value of PEWS in asse-ssing the severity of disease in critically ill children was explored. Results: The 1 069 severe cases of PICU ranged from 1 month to 13 years and 8 months, and PEWS score was (4.6±0.8) scores in the emergency room, and (5.1±0.5) scores in the PICU, so there were significant differences of the PEWS score between the death group [(8.0±0.5) scores] and the survival group [(4.8±0.8) scores] in the emergency room and PICU(all P<0.05). The PEWS score of the respiratory, nervous, circulatory and digestive system groups in PICU was (5.8±0.5) scores, while other systemic diseases (blood, kidney, poisoning, and so on) PEWS score was(4.2±0.5) scores; which showed significant differences between 2 groups(t=4.60, P<0.05). In PICU, the score of PEWS was greater than or equal to 4.7, which was the demarcation point to distinguish the critical condition and predict the death risk of the patient. Conclusions PEWS is of great significance for assessing the children sent to PICU.Patients with mainly respiratory, circulatory, neurological, and digestive system diseases have higher PEWS scores.The PEWS score of other system diseases is significantly reduced.It is suggested that PEWS is not able to reflect the disease of such a system and needs to be taken seriously.