The preparation and application of universal group O donor red blood cells (RBC) are a trend of future transfusion medicine. This article reviewed the technologies for producing universal RBC in recent years. One of them is modification of blood group antigens, which includes two basic methods. One of these two methods is enzymatic cleavage of the terminal immunodominant sugars from carbohydrate chains on the membrane of group A or/and group B RBC, in order to produce so-called enzyme-converted group O (ECO) RBC. ECO RBC have been produced from whole units of B RBC, which then survived normally when given to type A and O individuals in clinical trial. Because of the complexity of group A antigens, conversion of group A RBC (especially A1 RBC) to group O RBC is more difficult. Recently, a new bacterial glycosidase efficiently cleaving antigens on the surface of both A₁ and A₂ RBC has been obtained. Another method is pegylation, which camouflage the antigens on the surface of RBC with non-immunogenic molecules such as polyethylene glycol (PEG) in a non-specific way, to provide O, minor antigen negative phenotype RBC. The second technology is generating universal RBC from stem cells (such as hematopoietic stem cells, human embryonic stem cells) and human dermal fibroblasts, which will provide a new resource for blood supply. Great progress has been made, but a number of challenges still remain for using them in clinical transfusion, including scale-up, effectiveness and safety of prepared RBC. However, these researches will provide solutions for the problems in current transfusion, such as blood supply shortage, blood borne disease and emergency blood transfusion, and enhance the safety of clinical transfusions in the near future.