To explore the value of red cell distribution width (RDW), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and hemoglobin (Hb) A2 combined determination scheme for screening thalassemia.The RDW levels of thalassemia group and healthy control group were detected and compared. The efficiency of RDW for screening thalassemia was evaluated by receiver operating characteristic (ROC) curve. The diagnostic cut-off value of RDW was also acquired by Youden index. Then, 3 groups for thalassemia screening scheme were set, including MCV+MCH+HBA 2, MCV+MCH+RDW(>16.0)+HBA 2 and MCV+MCH+RDW(>15.15)+HBA 2. The performances of the 3 groups were evaluated through screening 621 clinical suspected cases of thalassemia.The RDW level in thalassemia group was significantly higher than that in healthy control group (P15.15, when the Youden index was the biggest among all data. The sensitivity, specificity, positive predictive value, negative predictive value, false negative rate and consistency rate of MCV+MCH+RDW(>15.15)+HBA 2 group was 75.46%, 48.83%, 26.50%, 89.06%, 24.54%, and 54.06%, respectively.The diagnostic cut-off value of RDW for thalassemia screening has been established. The group of MCV(15.15) has a best efficiency among the 3 groups to screen thalassemia.