Abstract: Strain S-16 isolated from sunflower soil taken from Sa-la Qi, Inner Mongolia exhibited a strong antagonistic activity on mycelial growth of Sclerotinia sclerotiorum. Affected fungal hyphae formed abnormal branches and bubble deformation structures. Sclerotial formation of S. sclerotiorum was inhibited in agar medium amended with 1% cultural filtrate of the strain. Control efficacies of sunflower white mold disease caused by S. sclerotiorum were 94.62% and 94.21%, respectively, when sunflower detached leaves and seedlings were sprayed with the strain at 2×10⁶ cfu/mL. The strain was identified as Bacillus subtilis according to its morphological, physiological and biochemical characteristics.