hEPO cDNA without non-coding ration was recombined with retrovirus vector pLXSN, pLNCX through DNA recombinant techniques. After these two recombinant plasmids were transfeeted the retrovirus packaging cell line PA317, G418 resistant clones could produce defective EPO cDNA recombinant retrovirus successfully which could infect NIH 3T3 target cells and make them form typical resistant clones in G418 selective medium. Moreover, in the genome of these infected target cells, hEPO cDNA was successfully integrated and expressed.