Disease analysis: AB type is a new blood type produced by the fusion of type A and type B, accounting for only about 9% of the global population, and it is the shortest blood type on the earth. According to the current clinical evidence, more than 90% of ABO hemolytic children are O type, and infants are A type or B type. This ABO blood group incompatibility between mother and child is not uncommon in all pregnancies, accounting for about 20%. However, hemolytic disease of newborn is relatively rare, only about1150, and most of the symptoms are mild and often ignored.