The present invention relates to a plant extract in the mixed composition in plants powdery mildew control effect. The production method of the present invention plant powdery mildew control the plant extract mixture composition which effects are, rhubarb roots, goldthread root, after preparing the green tea leaves, using column chromatography methods and concentrated extract pulverized rhubarb roots Cri sofa play, and to the emodine ingredients ready to pure separated from each other, barberry root, ground root extract concentrated after column after using chromatographic methods and prepare it purified the berberine ingredients, crushing the green tea leaf extract concentrated green tea leaves crushed after separation of the components by catechin, a sofa Cri play separation: consists in prepared by mixing 1 volume ratio: catechin 1:: in emodine: berberine 1: 1. There is provided a plant extract in the mixed composition with a preventive effect on powdery mildew harmful to the crop plants by the present invention, further, there is provided a method for producing a plant extract in the mixed composition in controlling effect on powdery mildew plant. Powdery mildew, rhubarb, barberry root, green tea, couch creative play, the emodine, berberine, catechin