The invention discloses a novel plant source insecticide for fruit trees, a preparation method and an application thereof, and belongs to the field of preparation technology of insecticide. The insecticide comprises the following raw materials in parts by weight: patrinia, tobacco scraps, Aconitum soongaricum, pyrethrum, paulownia sawdust, Sophora alopecuroides, officinal magnolia barks, Chinaberry, Chinese ash leaves, Celastrus angulatus, ash barks, flavescent sophora roots, Euphorbia soongarica, bitter sow thistle, ailanthus, lettuces, mints, thunder god vine roots, weeping willow leaves, castor-oil plants and water. The novel plant source insecticide for fruit trees is prepared by the following steps: extraction of soup, condensation, drying, crushing, sieving, disinfection, etc. The insecticide does not have toxic components, residuals, and pollution, and is green and environmentally friendly; the insecticide can be used for effectively controlling red spider mites, Aonidiella aurantii, fruit flies, blister mites and other plant insects, one-time killing rate reaches above 95.53%, and the insects do not have drug resistance.