The invention relates to a method for preparing ultra-micro peony flower powder from peony flower serving as raw material, as well as the ultra-micro peony flower powder prepared by the method and application of the ultra-micro peony flower powder. The ultra-micro peony flower powder can be powder or can be further processed into instant ultra-micro peony flower powder preparations in the forms of granules, tablets, capsules and the like, can be used alone as a nutritious food, a health food, food for athletes, a beauty mask, bath supplies and the like, and also can be used together with other nutritious foods, health foods and foods for athletes. Besides, the ultra-micro peony flower powder has the functions of adjusting blood fat, stabilizing blood pressure, detoxifying for beautification, delaying senescence, enhancing the immunity of human bodies, and the like, thereby having very broad development and application prospects in the fields of food industry, health food and the like.