The invention discloses a botanical insecticide for fruit trees and a preparation method and an application thereof, and belongs to the technical field of insecticide preparation. The botanical insecticide for fruit trees comprises the following raw materials: scutellaria baicalensis, purslane, datura stramonium, pyrethrum, paulownia leaf, sophora alopecuroide, magnolia cortex, melia azedarach, wasabi, chinaberry bark, ash bark, sophora flavescens, euphorbia soongarica, anabasis aphylla, dioscorea zingiberensis, lettuce, mint, tripterygium wilfordii, salix babylonica leaf, Chinese prickly ash and water. The botanical insecticide for fruit trees is prepared by steps of medical liquid extraction, concentration, drying, crushing, sieving, sterilization and the like. The botanical insecticide for fruit trees has advantages of nontoxic component and no residue, is pollution-free, green and environmentally friendly, and will not cause environmental pollution. The botanical insecticide for fruit trees can effectively control plant insects such as citrus bud mite, Aonidiella aurantii, papilionoidea, tortrix and the like. One-time killing rate reaches 95.56% and above. The plant insects have no drug resistance and can be used for 4-6 years.