Abstract: Event-specific qualitative PCR detection method has advantageous because of its specificity and hence be used in the Chinese detection standards.In this study,an event-specific transgenic detection method for 'Huanong No.1',a transgenic papaya variety with high resistance to papaya ringspot virus,and widely planted in Guangdong Province,was established.By using the thermal asymmetric interlaced PCR(TAIL-PCR) technique,the flanking sequences of the exogenous integration in the genome of 'Huanong No.1' were cloned and sequenced with the specific nested primers based on Nos promoter near the right border(RB).According to these sequences,two pairs of PCR primers were designed to amplify the fragments with sizes of 753 and 298 bp respectively,and spanning the exogenous integration and papaya genome.Hence,the qualitative PCR assays were established for 'Huanong No.1'.The detection sensitivity reached to 0.05%.Furthermore,this method can also be used in various organs of papaya,such as seeds,fruits,fruit skins etc.