The invention belongs to the field of health food processing technologies, and relates to a preparation method and application of a patrinia villosa root extractive. 75% ethyl alcohol is used for performing digestion on dried patrinia villosa root powder at the room temperature, then ultrasonic extraction is performed, standing and filtering are performed, and reduced pressure distillation is performed on filter liquor, so that crude extract is obtained; appropriate water is added to the crude extract to dilute the crude extract to be a suspension, extraction is performed for three times with petroleum ether and ethyl acetate, ethyl acetate layer extraction liquor is combined, reduced pressure condensation is performed on the ethyl acetate layer extraction liquor, then the ethyl acetate layer extraction liquor is dried to constant weight in a freeze mode, and the ethyl acetate extractive is obtained for use. The patrinia villosa root extractive has good capacity for clearing DPPH free radicals and ABTS free radicals. The method of the patrinia villosa root extractive can be used for developing new antioxidant in the fields of food, medicine, health food and the like, and is beneficial to industrial production.