The invention belongs to the technical field of agricultural sustainable development, relates to preparation of organic preparations and in particular relates to an organic preparation for controllingcruciferous vegetable club root and application thereof. The organic preparation is composed of organic raw materials and decomposition-promoting ingredients, wherein the organic materials include but not limited to one or more of crop straws, saw dust and other solid organic materials and molasses, alcoholic fermentation liquor and other liquid organic materials; the decomposition-promoting ingredients include but not limited to one or more of special microbes and organic catalysts; and a ratio (mass) of the organic raw materials to the decomposition-promoting ingredients is (95-100):(5-0).The invention further discloses a preparation method and application of the organic preparation. The organic preparation disclosed by the invention is ecologically environment-friendly and is applicable to soil with high incidence of club root after continuous cropping of various cruciferous vegetables. The quantity of plasmodiophora brassicae woron in soil and the incidence rate of the club rootof crops can be effectively reduced after treatment, the sterilization rate and the club root control rate respectively reach 60-90%, and the yield of the crops is obviously increased.