Abstract: Objective　To investigate the application value of trapezoid microplate method in determining ABO bloodgroup in blood donors. Methods　The known bloodgroup samples were collected. The samples and their forward and reverse test parameters of ABO bloodgroup were detected by orthogonal design and trapezoid microplate method. These test methods were routinely used for blood sample testing among blood donors. Results　A total of 24 922 blood donor samples were determined by trapezoid microplate method， which showed that the correct interpretation at one time was 99.6%. However, 5 cases of ABO bloodgroup detected in moving vehicle for donation were wrong， and 2 cases of A2 group，1 case of B3 group and 1 case of irregular antibody were also found. Conclusions　The correct interpretation at one time of trapezoid microplate method to detect ABO bloodgroup is high， and the ability of trapezoid microplate method to detect ABO subgroup and irregular antibody is great. Trapezoid microplate method brings about the standardization，automation of ABO bloodgroup test and digitization of test results， and the test results are issued automatically on net. It is simple， rapid and accurate for trapezoid microplate method to detect a large number of blood donor samples，and it is worth that trapezoid microplate method is used to the determination of ABO bloodgroup extensively.

Key words: Trapezoid micro plate method, ABO blood group