Objective To explore the conversion rule of serological blood group and blood group substance after successful allogeneic hematopoietic stem cell transplantation, and to provide theory for clinical special blood type identification and blood transfusion. Methods The growth cycle of recipient WBC and RBC, RBC chimera, blood group antibody production and remaining in full transition were observed. Conversion rule of blood group substance, contradiction between cells typing and sera typing were detected by saline medium tube method and microcolumn gel method after stem cells transplantation. Results The average time of engraftment in 21 recipients was about 18.6 days, RBC growth cycle in 8 major blood type incompatibility was 56.6days, 25.9 days in 9 minor blood type incompatibility, 67 days in 4 bidirectional blood type incompatibility (P<0.01). The ratio of RBC chimeric growth was 1∶9, gradually conversed to donor's blood group. Residue of recipient anti-A(B) was left after conditioning regimen, disappeared after full transformation, and recipient anti-A(B) was conversed to donor's blood type in major blood type incompatibility. 5 A blood type recipient donated by O blood type blood generated anti-B instead of anti-A, 3 B blood type recipient generated only anti-A instead of B in minor blood type incompatibility, and 1 AB blood type recipient donated by A did not generate anti-B. Among 4 bidirectional blood type incompatibility, 2 B blood type recipient donated by A blood type blood did not generate anti-B, 2 A recipient by B could not produce anti-A. Recipient blood group substance helped original ABO blood type substance remain unchanged.Conclusion Among patient with allogeneic hematopoietic stem cell transplantation, recipient's ABO and RBC blood type can be conversed to donor's, but there is significant difference between patients of serological blood group and of normal people(P<0.01). Recipient blood group substance helps original ABO blood type substance remain unchanged (P>0.01).