Abstract: Transfusion is an important means for medical treatment, but it has many syn-dromes shch as transfusion-associated graft-versus-host disease, it's occurrence rate of 5% and above 90% death-rate. Now many experts think the only proven method is using blood irradiator to prevent this disease. It can make lymphocyte of blood product inactive, so that it can't attack human body. Therefore, using irradiation blood is a trend, and blood irradiator may play an important role in medical field. This article summarized studys of blood irradiator application, including the meaning of blood irradiation, selection of the dose for blood irradiation and so on.