First,we use human hepatic RNA as templ ate and got CD55 cDNA by PT-PCR. Secondly, CD55 cDNA is combined with promoter a nd polyA of human α-globin, then inserted into plasmid pGEM-5zf. At last,we got a transgenic constructs' of pGEM-5zf-α-globin-CD55 cDNA'. The constructs ma y use to found human CD55 transgenic animal model.