The invention relates to a preparation method of a medicine for treating gall-stone. The preparation method comprises the following steps: adding 25000ml of water into 260g of maidenhair, 250g of caricina Christ, 230g of scirpus tabernaemontani, 230g of asparagus, 210g of maoguashu, 180g of myriaceis nepalensis, 200g of circaea mollis, 180g of grewia biloba, 160g of zostera marina, 150g of kycopodium fargesii, 150g of pteris nervosa, 130g of evening primrose, 120g of myrsinaceae, 120g of day lily, 100g of anaphalis lacteal, 110g of mntha rotundifolia, 100g of roots of little leaf dogwood and 80g of liquorice, heating for 5 hours under the back flow condition, filtering so as to obtain filtering residues 1 and filtrate 1, adding 20000ml of water into the filtering residues 1, heating for 3 hours under the back flow condition, filtering so as to obtain filtering residues 2 and filtrate 2, adding 10000ml of water into the filtering residues 2, heating for 1 hour under the back flow condition, filtering so as to obtain filtering residues 3 and filtrate 3, combining the filtrate 1, the filtrate 2 and the filtrate 3, and concentrating until being 10000ml, thereby obtaining the medicine.