To discuss the serological character of ABO subgroup through AxB(ABO subgroup) identification,and ensure the safety of blood transfusion.The serological character of the specimen from the donor was confirmed as AxB,and the major point of identification was distinguishing from B(A).The vitro result may reflect the vivo reaction.ABO subgroup can go further to do molecular analysis.The transfusion rule of ABO subgroup is the same type or the compatible type.