The invention belongs to a Chinese patent medicine which relates to externally-applied liquor for treating dermatosis and a preparation method thereof. The externally-applied liquor is prepared from Lightyellow Sophora Root, amur corktree bark, cnidium fruit, broom cypress fruit, radix sileris, honeysuckle, stemona root, pseudolarix, camphor, dittany bark, bitter peony bark, saffron crocus, ginseng, dandelion, sea buckthorn fruit, semen coicis, wrinkled gianthyssop, mulberry leaf, radix puerariae, bezoar, liaogewang, cassia nomame thorn, centipede and toad venom. The liquor has a very strong killing and preventing action to the bacteria and the fungi of staphylococcus aureus, colibacillus, candida albicans, pseudomonas pyocyanea, mould fungus and the like. The liquor has unique curative effect to the dermatosis of psoriasis, dermatitis, acne, beriberi, onychomycosis and the like. The liquor has little possibility of relapse after recovering and lower cost and can be accepted by all the common people. By clinic, feedback and follow-up survey, the total effective rate of the invention reaches more than 94%.