To accurately look at the blood type, we must first have a correct understanding of the human blood type. There are dozens of blood types in the human body so far, but only two are widely used in clinical practice, one is ABO blood type and the other is Rh. ABO blood types are clinically divided into four types, namely A blood type, B blood type, AB blood type and O blood type. Rh blood type is divided into two types according to whether or not the red blood cell membrane contains D antigen, those containing D antigen are Rh positive and those without D antigen are Rh negative. So for a person’s blood type to be properly understood, one must know the types in ABO blood group and also the types of Rh blood group.