[Objective] To isolate and identify the antimicrobial active component extracted from fermentation broth of antagonistic actinomycetes strain G-19 against peach crown gall(Agrobacterium tumefaciens).[Methods] Sephadex LH-20 chromatography,HPLC and mid-dle-pressure chromatography were used for isolation and purification.LC-MS,NMR were ap-plied to identify structure of the active component.[Results] Compound G-19-I was isolated and structurally identified as 1,2-benzenedicarboxylic acid,1,2-dibutyl ester(DBP)...