The invention discloses a medicine for treating damp toxin immersed type edema and a preparation method of the medicine. The medicine comprises the following bulk drugs: soft water coptis, platycodon grandiflorum, fructus arctii, stellaria neglecta, blacken saussurea herb, herba schizonepetae, drymotaenium miyoshianum, rhizoma atractylodis, daimyo oak leaves, periostracum cicada, radix saposhnikoviae, paleyellow elsholtzia herb, radix sophorae flavescentis, ligularia lapathifolia, radix puerariae, fleshy spurge pistil and stamen, gardenia, patrinia heterophylla, honeysuckle, periploca forrestii roots, dandelion, phellodendron amurense, swertia erythrosticta maxim, cortex dictamni, fructus forsythiae, cirsium esculentum, berberidis, andrographis paniculata, lobelia chinensis, physalis angulata, poria cocos, rhizoma alismatis, rubus rufo-lanatus, polyporus, cortex periplocae, ricepaperplant pith, fructus kochiae and mountain magnolia flowers. The medicine has the beneficial effects that the medicine has the efficacies of clearing away heat, drying dampness and inducing diuresis to reduce edema, mainly treats damp toxin immersed type edema, and has the characteristics that the medicine takes effect rapidly, is high in efficiency, definite in curative effect, high in safety, and short in treatment course, and has no toxic or side effect; the drug efficacy reaches a focus directly; the drug resistance does not generate easily; the preparation process is simple and convenient; the cost is low; and the possibility of relapse after cure is low.