Abstract: ［Objective］An antagonistic bacterial strain YB-3 against Rhizoctonia solani was isolated from soils．［Methods］ Antagonistic strains were isolated by a reporter strain method． YB-3 was identified based on morphology observation，physiological and biochemical characterizations，Biolog，G + C content and 16S rDNA sequence analysis．The antagonistic spectrum and the properties of the inhibitor produced by Bacillus amyloliquefaciens YB-3 against plant pathogenic fungi and bacteria were investigated by means of plate two-way cultivation and disc diffusion method．［Results］ The strain YB-3 against Rhizoctonia solani was identified as Bacillus amyloliquefaciens． The antagonistic results showed that it had distinctively inhibitive effects on 14 pathogenic fungi and 7 bacteria． In addition，it also had inhibitive effects on strains from genus Bacillus to which YB-3 belongs． Antagonistic properties of B．amyloliquefaciens YB-3 was thermostable，acid resistant，and protease sensitive． ［Conclusion］ Bacillus amyloliquefaciens YB-3 was isolated and characterized which had distinctively inhibitive effects on Rhizoctonia solani and had broad-spectrum，highly efficient to plant pathogens．