Objective　To explore the risk factors and clinical characteristics of cytomegalovirus (CMV) infection after allogeneic hematopoietic stem cell transplantation (allo-HSCT) in children. Methods　The clinical data of allo-HSCT in 269 children from January 2016 to December 2018 were collected. The copies of CMV-DNA in whole blood after transplantation were monitored. The incidence, time, risk factors, and prognosis of CMV infection were analyzed. Results　A total of 269 cases (167 males and 102 females) were included and median age was months (33 - 115 months). Among them, 165 cases had CMV infection and the infection rate was 61.3%. The infection occurred 23 days (15 - 34 days) after transplantation, and the infection lasted 38 days (25 - 66 days). Multivariate logistic regression analysis showed that transplantation age > 65 months and grade Ⅱ-Ⅳ aGVHD after transplantation were risk factors for CMV infection, while sibling donor hematopoietic stem cell transplantation (Sib-HSCT) could reduce the incidence of CMV infection (P < 0.05). The occurrence of grade Ⅱ-Ⅳ aGVHD and the use of cord blood transplantation are associated with the incidence of refractory CMV infection (P < 0.05). The difference of the overall survival rate and disease-free survival rate between the refractory CMV infection group and the non-refractory CMV infection group was statistically significant (P < 0.05). Conclusion　The risk of CMV infection can be increased by older children and Ⅱ-Ⅳ aGVHD, while the risk can be reduced by Sib-HSCT. Refractory CMV infection was likely to occur after umbilical cord blood transplantation, and the initial detection time of refractory CMV infection was early and the peak value was high.