Abstract: To investigate the biocontrol activity of Streptomyces corchorusii strain NF0919 and Bacillus subtilis DJ-6 WP to grape downy mildew, we had determined the indoor toxicity of the supernatant of S. corchorusii strain NF0919,1.0×10₁₁cfu/g B.subtilis DJ-6 WP, mancozeb and dimethomorph on Plasmopara viticola by using leaf disc method, respectively,and the field control tests were conducted. The results showed that the EC₅₀ values of the supernatant of strain NF0919,1.0×10₁₁cfu/g B.subtilis DJ-6 WP, mancozeb and dimethomorph were 96.2859, 86.6038,69.9472 and 7.2636 μg/mL, respectively. The values of field control effect used in preventive experiments for grape downy mildew on the 7th day after 2 times spraying with 20 times liquid of the supernatant of strain NF0919 and 1000 times liquid of 1.0×10₁₁cfu/g B.subtilis DJ-6 WP were 71.55% and 70.71%,the values of field control effect of 14th day after 2 times spraying were 67.54% and 68.19%, respectively. The values of field control effect used in curative experiments on the 7th day after 2 times spraying with 20 times liquid of the supernatant of strain NF0919 and 1000 times liquid of 1.0×10₁₁cfu/g B.subtilis DJ-6 WP were 59.72% and 56.07%,the values of field control effect of 14th day after 2 times spraying were 56.88% and 57.46%, respectively. The field control effect of two kinds of supplied test biocontrol agents were equivalent.The protective effect between each of supplied test biocontrol agents and 300 times liquid of of 50%mancozeb WP had not significant difference, but there were significant difference at the efficacy between each of supplied test biocontrol agents and 200 times liquid of 40% dimethomorph SC. In conclusion, the S.corchorusii strain NF0919 and B.subtilis DJ-6 WP have certain biocontrol potential to grape downy mildew and value of development.