Rh-negative blood type is panda blood, Rh-negative blood belongs to the Rh blood group system, the human blood group system in addition to the ABO blood group system, in the clinical use of the Rh blood group is often used, Rh blood type was first discovered from the Indian rhesus monkey red blood cell membrane. The Rh blood group is divided into two categories according to whether there is still D antigen on the red blood cell membrane: those containing D antigen are Rh-positive, and those without D antigen are Rh-negative. D antigen has strong antigenicity and can stimulate the body to produce antibodies for antigen-antibody reaction, so Rh-negative people will produce antibodies if they come into contact with RH-positive blood and are prone to antigen-antibody reaction. At the same time, Rh-negative people are very rare in China, less than one thousandth of the whole population. Therefore, Rh-negative blood is called panda blood.