The invention discloses an externally-applied traditional Chinese medicine for treating prostatic diseases. The medicine comprises two independent composing prescriptions which are alternately applied, wherein the first composing prescription comprises radix angelica sinensis, cowherb seed, woodwardia japonica, morinda root, epimedium, dodder, prepared rhizoma cyperi, monkshood, Chinese mugwort leaf, fennel, cinnamon, eupatorium, evodia, pinellia tuber, dried orange peel, cortex moutan, peach seed, rhizoma corydalis, lindera aggregata, rhubarb, rhizoma sparganii, zedoary, fenugreek, suberect spatholobus stem, leonurus, borneol and white spirit; the second composing prescription comprises golden cypress, sophora flavescens, patrinia, sargentg loryvine stem, rhubarb, mirabilite, red sage root, safflower, plantain herb, corrugated paper, lychee seed, toosendan fruit, ground beetle, jackinthepulpit tuber, bupleurum, snakegourd fruit, achyranthes bidentata, grass leaved sweetflag, sapanwood, areca peel, pangolin, gleditsia sinensis sting, coptis, loofah sponge, cape jasmine fruit, rhizoma cimicifugae, Sichuan pepper, ginseng and a proper amount of white spirit. The medicine disclosed by the invention has the beneficial effects that the medicine per se has a good treatment effect and is short in pathway of reaching lesion; the stimulation of the medicine on intestines and stomach is avoided; a novel way is developed for treating the prostatic diseases.