The invention discloses an oral liquid for treating organic constipation. The oral liquid comprises raw materials in parts by weight as follows: 0.5-2 parts of aluminium stearate, 0.1-0.8 parts of sodium carboxymethyl starch, 8-15 parts of sanguinarine, 3-8 parts of resveratrol, 0.5-3 parts of vitamin B6, 1-5 parts of tea polyphenol, 2-6 parts of carotene, 5-10 parts of aloe juice, 2-5 parts of fructooligosaccharide, 4-12 parts of honey and 24-36 parts of mannitol. The invention further discloses a preparation method of the oral liquid. Products such as the sanguinarine, the tea polyphenol, the resveratrol and the like have a synergistic effect, so that the oral liquid takes effect quickly when treating constipation and can rapidly relieve constipation symptoms and relieve pain of patients. The oral liquid is convenient to use, sweet in taste, acceptable for the patients, rich in raw material source, low in cost, high in quality and free of toxic or side effects during use, has no other adverse reactions after taking and has a good use effect.