[Objective] Research on the fermentation conditions to K1, the antagonistic bacteria inhibiting Botrytis cinerea. [Methods] Fermentation medium and fermentation conditions were optimized in OD₆₀₀ index usingresponse surface methodology. By the Plackett-Burman experiment the most significant three factors were yeast ex-tract, p H, inoculum. After Box-Behnken experiment and response surface methodology, the optimum fermentationwas determined. [Results] The optimum fermentation medium was 1% starch, 1.8% yeast extract, 1.5% K₂SO₄. Theoptimal fermentation conditions were as follow: pH 6.8, inoculation amount 2.8%, temperature 25 ℃, rotation speed 130 r/min, liquid volume of 100 mL/250 mL. [Conclusion] The OD₆₀₀ of K1 was 1.490 after 16 h fermentation. It wasmuch higher than 0.864, the OD₆₀₀ before optimization. The grow rate of K1 was increased significantly. Inhibitionzone diameter was 49 mm. It was higher than 43 mm, the inhibition zone diameter before optimization.