The invention discloses a medicine for treating urethral calculus and a preparation method thereof, and belongs to the field of traditional Chinese medicine. The medicine is composed of the following effective raw materials: water hyacinth, gomphostemma root, aeginetia indica, common leafflower herb with root, Chinese brake herb, juniperinum, Indian damnacanthus herb, bergia ammannioides roxb, edelweiss, randia cochinchinensis, juniper, eragrostis pilosa, horsetail, hawkweed, Japanese snailseed root and gold sakura. The raw materials of the medicine are compatible, and accord with the theory of traditional Chinese medicine and modern medicine and pharmacology; the medicine has the effects of activating qi and resolving stagnation, treating stranguria and removing calculus, resisting inflammation, promoting urination, dispelling the wind and relieving pain, thus the medicine has unique effects on the symptoms, such as frequent micturition, micturition pain, copious urine, pyuria and hematuresis caused by the urethral calculus. The medicine is convenient to take, is safe, reliable and free of toxic and side effect, and no recrudescence is caused after healing. The medicine has an accurate curative effect for treating urethral calculus, and achieves the aim of treating both symptoms and root causes, thus the medicine is worth being promoted and applied in clinic widely.