On the basis of morphological, physiological and biochemical characterization, the antagonistic bacterium strain L1 against Phyricularia grisea was identified. The strain L1 was bacilliform, Gram-positive, fuscous and draped colonies, aerobiosis. The result showed that the strain L1 belongs to Bacillus subtilis. The antimicrobial activity of fermentation liquid reached the highest after 5 days-old cultures. And inhibitory rate accounted for 74.57%, but it had not changed along with the time increase. The activity effect of antimicrobial substances was insensitive to heat. The filtrated Bacillus subtilis strain L1 was precipitated in grades with the ammonium sulfate to draw the antimicrobial proteins and crude proteins were obtained. One crude protein drawn with ammonium sulfate at 50%~60% saturation showed strong antimicrobial activities to Phyricularia grisea. Average radius was accounted for 0.51 cm.