Abstract: Results from PCR and southern-blot analysis conformed that the target gene was integrated into the genome of T_2 transgenic papaya (Carica papaya) plants with replicase gene of papaya ringspot virus (PRSV). These transgenic papaya seedlings in 7-8 leaf stages were mechanically inoculated respectively with three severe strains of PRSV in South China. They showed a high resistant to all strains of PRSV. By transplanting these seedlings to field, no any symptom appeared in these transgenic plants during 9 months. On the contrary, the control plants showed very severe symptoms.