Phytophthora root and stem rot, caused by an oomycete pathogen Phytophthora sojae, is one of the most devastating diseases in soybean production. In our previous study, we introduced a broad-spectrum disease resistant gene hrpZm into the soybean cultivar ’Williams 82’by the Agrobacterium-mediated transformation to generate the transgenic event B4 J8049,which exhibited high resistance to P. sojae and approved for environmental release. To advance safety assessment and application of the transgenic soybean event, we analyzed the insertion site of the foreign T-DNA in the genome of the event B4 J8049 using the thermal asymmetric interlaced PCR（TAIL-PCR）, and established the event-specific detection method based on the flanking sequence at the right border of the T-DNA insertion. Southern blot analysis confirmed the single-copy insertion of the foreign T-DNA in the soybean genome.Three nested specific primers based on the T-DNA sequence and the arbitrary degenerate primers were designed to amplify the right border flanking sequence by TAIL-PCR. BLAST analysis（https://soybase.org/） revealed that the foreign T-DNA was inserted into the position 187 824 on the soybean chromosome 8 in the reverse way. Based on the flanking sequence of the right border, an event-specific detection method was established for the transgenic soy-bean B4 J8049 and its derivative products.