Abstract: Virulence of seedvax (amicarthiazol), saikuzuo (bismerthiazol) and carboxin to Xanthomonas citri、X. oryzae pv. oryzae、X.campestris pv. glycines and Rhizoctonia cerealis were determined , and the relation of their activity with their composition were analysised , Furthermore, their effects on growth, respiration and fungiactive mode to X. citri were taken into investigation . The results indicated that virulence mechanism of seedvax is interrelated to that of saikuzuo and carboxin , seedvax possibly attack any targets of the respiration pathway and other unknown bio chemical sites, seedvax is characterized with poly active location when transported in bio metabolic ways.