Irregular antibodies are blood group antibodies other than anti-A and anti-B. Irregular antibodies are one of the items that must be checked before blood transfusion, which are divided into three aspects: First, when the blood donor’s serum or plasma is positive for irregular antibodies, it cannot be transfused to the patient. Once the patient’s red blood cells contain antigens corresponding to irregular antibodies in the donor’s plasma, an antigen-antibody immune reaction will occur, resulting in a hemolytic transfusion reaction. Usually the local blood supply unit, also known as a blood center, will prepare this plasma into antibody serum for the identification of rare blood types, which can reduce the waste of blood. Second, when the patient’s plasma or serum is positive for irregular antibodies, the donor’s red blood cells should be selected without the antigens corresponding to the irregular antibodies in the patient’s plasma, and likewise, once the red blood cells containing the antigens corresponding to the patient’s plasma are imported, an antigen-antibody immune reaction will occur, resulting in a hemolytic transfusion reaction. Third, when a pregnant woman is positive for irregular antibodies in her serum or plasma, the titer of irregular antibodies can be further tested, and according to the titer of antibodies, early intervention can be made to avoid unnecessary harm to the fetus or newborn, to reduce the occurrence of neonatal hemolytic disease, and to improve the health quality of the newborn.