Objective: To analyze the cause of ABO typing discrepancy and to explore the strategy of blood transfusion. Methods: ABO blood group was identified by serological method, and the cases with ABO typing discrepancy were confirmed by molecular biological method. Results: Seventy-four cases of ABO typing discrepancy were detected in 84 487 cases, the discrepancy rate was 0.09%. Removing repeated cases, there were 67 cases: red blood cell antigen weakened 43 cases, blood group antibody weakened 9 cases, both antigen and antibody weakened 2 cases, subtypes 12 cases, others 1 case. In 36 hospitalized patients of ABO typing discrepancy, 25 cases received blood transfusion, and 22 were patients with hematological disorder. Excluding subtype cases, analysis of the effect of blood transfusion between 15 cases of same ABO genotype RBC and 5 cases of O blood type washed RBC showed no significant difference (P=0.225>0.05). Conclusions: The largest number of ABO typing discrepancy are patients with hematological disorders. Compatible ABO or same gene type RBC should be used in clinical blood transfusion. Both serological and molecular biological methods should be taken into account.