A-positive blood means that a person’s blood type is A in the ABO blood group system and RH positive in the RH blood group system. Because there are dozens of human blood group systems, there are only two that are widely used in clinical practice: 1. One is the ABO blood group system, which divides human blood groups into four, namely, A blood group, B blood group, AB blood group and O blood group. 2. The other is the RH blood group system, which divides human blood groups into two, one is RH-positive, the other is RH-negative, and the latter means that red cell membranes contain the D antigen, and RH-positive is that red cell membranes contain the D antigen. Positive means that the red blood cell membrane contains D antigen, RH negative means that there is no D antigen on the red blood cell membrane. In China’s Han population, the vast majority of people are RH positive, and there are very few RH negative people. Therefore, A-positive blood means A blood in the ABO blood group system and RH-positive blood in the RH blood group system.