It is possible to have a child with blood type O if the parents are blood type B. If the parents are blood type B, then both parents have a blood type gene of BB or BO. In the first case, if both parents have BB, then the child of the two parents must also have BB and have B blood type. In the second case, if both parents have the BO blood group gene, then the child of the two parents has three possible blood group genes, BB, BO, and OO, and the child’s blood group may be B or O. The third case is that both parents have the BO blood group gene. The third scenario is that if both parents have BB and BO blood genes, then the child’s blood genes may be BB and BO, and then it will show B blood type. Therefore, it is possible to have a child with blood type O if the parents have blood type B, but the final result will depend on the test results.