The invention belongs to the technical field of traditional Chinese medicines, and particularly relates to an external plaster for dredging veins and application and a preparation method thereof. The traditional Chinese medicine composition is mainly prepared from leech, scorpion, centipede, angelica sinensis, radix scrophulariae, coix seed, golden cypress, honeysuckle, astragalus membranaceus, liquorice and the like, and the ointment disclosed by the invention can be used for treating lower limb deep venous thrombosis, thrombophlebitis, thromboangiitis obliterans, lower limb arteriosclerosis obliterans and the like, and has the advantages of being easy to attach, and easy to penetrate human skin; and the percutaneous absorption is realized, so that the effect is fully exerted. Compared with oral medicines and injections, the traditional Chinese medicine composition has the advantages of small toxic and side effects, direct lesion, quick absorption, instant effect, wide application range and no obvious contraindication.