Abstract: Objective:To construct a nomogram prediction model for predicting the risk of cytomegalovirus(CMV) infection in patients with β-thalassemia major after hematopoietic stem cell transplantation (HSCT), and to evaluate its predictive value.Methods:Clinical data of patients with β-thalassemia major undergoing HSCT in the Department of Hematology of the First Affiliated Hospital of Guangxi Medical University from July 2020 to June 2022 were collected and divided into infected group and non-infected group according to the outcome of CMV infection.Independent samples t-test, nonparametric test, chi-square test, LASSO regression method were used to determine the prediction predictors included in the nomogram model.The value of the model was evaluated and verified by receiver operating characteristic curve (ROC), calibration curve, C-index and decision curve analysis(DCA), and the Bootstrap method was used for internal validation.Results:Age, HLA matching, cyclosporin A, serum ferritin, CD34 and acute graft-versus-host disease were predictive factors of the nomogram model for CMV infection after HSCT of β-thalassemia major.The C-index of the nomogram was 0.682 (95% CI:61.0% -75.4% ), the C-index calculated by internal validation was 0.644, the area under the ROC curve was 0.682, and the result of DCA was 0.09-0.83.Conclusion:The nomogram model is constructed based on age, HLA matching, cyclosporin A, serum ferritin, CD34 and acute graft-versus-host disease for the first time.The model is effective in predicting the risk of CMV infection in patients with β thalassemia major after HSCT, which was conducive to optimizing clinical diagnosis and treatment of patients and improving the quality of life of patients.