The possibility of hemolysis exists in a child conceived from a mother with type O blood and a father with type AB blood. Hemolytic disease of the newborn refers to isoimmune hemolysis caused by the incompatibility of the mother’s and fetus’s blood groups, of which AB0 blood group incompatibility is the most common. Its pathogenesis is mainly carried by the father’s genes and the mother does not have the dominant fetal red blood cell blood group antigen, through the placenta into the mother, stimulate the mother to produce the corresponding blood group antibody, when the incomplete antibody enters the fetal blood circulation, and the red blood cells of the corresponding antigen binding, in the lead to the monocyte-macrophage cell system is destroyed, causing hemolysis. AB0 hemolysis refers to the situation where the mother is type 0 and the fetus is type A or B. AB0 hemolytic disease does not occur when the mother is AB and the fetus is type 0. Most AB0 hemolysis occurs in the first pregnancy because the type 0 mother has been stimulated by natural A or B blood group substances prior to the first pregnancy and produces anti-A or anti-B antibodies, leading to the development of hemolysis in the child.