Objective：To explore the effect of admission anemia on the prognosis in children with moderate to severe traumatic brain injury（TBI）. Methods：This retrospective cohort study was conducted in Department of Critical Care Medicine，Children’s Hospital of Chongqing Medical University between May 2012 and October 2014 including patients with moderate to severe traumatic brain injury[Glasgow coma scale（GCS） 3 to 13]. The patients were divided into non-anemia group（Hb≥100 g/L） and anemia group（Hb<100 g/L） according to admission hemoglobin level. Non parametric test and chi square test was used to explore the differences between the groups. Multivariate logistic regression was used to identify risk factors related to mortality. Results：Totally 109 patients were enrolled and 17 patients among them died in hospital. The admission hemoglobin of 52 patients was less than 100 g/L. Compared with those of patients without admission anemia，the ages were younger，GCS and PTS were lower，and the length of hospital stay was longer in pa－tients with admission anemia（P<0.05）. Univariate analysis found that admission anemia，hyperglycemia，GCS<8，pediatric trauma score（PTS）<8，abnormal pupil reflex ratio and polytrauma significantly influenced mortality（all P<0.05）. Multivariate logistic regression analysis showed that admission anemia（AOR=9.383，95%CI=1.086 to 81.094，P=0.042），abnormal pupil reflex（AOR=23.121，95%CI=3.680 to 145.270，P=0.001） and admission hyperglycemia（AOR=15.181，95%CI=2.019 to 114.160，P=0.008） were independent risk factors for death in children with moderate or severe TBI. Conclusion：The admission anemia is an independent risk factor for the mortality of pediatric patients with moderate to severe TBI. And admission anemia is associated with prolonged hospital stay.