Vegetable gray mold caused by Botrytis cinerea is one of the most common and serious diseases of greenhouse vegetables. There are few reports on biological control of this disease by actinomycetes. Streptomyces have antagonistic effects on plant pathogens, so they can be used as biocontrol bacteria for development and utilization. In this study, the liquid fermentation of Streptomyces cavourensis was employed to determine the antagonistic effect against B. cinerea via plate confrontation assay, furthermore, the fermentation conditions under which the S. cavourensis produced the maximum antibacterial substances were determined. The results showed that the best fermentation medium was basal medium, the best inoculum size was 5%-6%, the best fermentation temperature was 28 ℃, the best fermentation pH value was 6-8, the best fermentation culture time was 9-11 d, the best carbon source was sucrose, and the best nitrogen source was ammonium nitrate.