Irregular antibodies are antibodies to blood groups other than anti-A and anti-B in the serum. Clinically, blood group testing refers to the testing of ABO blood group and RH blood group, and the traditional saline blood group testing and cross-matching test are only effective for ABO blood group system, but not for many other blood group systems. Irregular antibodies are tested in cases requiring blood transfusion or pregnancy to prevent immune reactions when irregular antibodies bind to the corresponding antigens during transfusion or delivery, which may cause fever and chills in mild cases or hemolysis in severe cases, leading to life-threatening conditions. Irregular antibodies can lead to neonatal hemolytic disease, which affects the development of newborn organs and intelligence, and can threaten the life of the newborn in serious cases. Those who need blood transfusion and pregnant women should be screened for irregular antibodies, and blood donors should do a good job of screening to prevent transfusion of blood containing irregular antibodies to others.