The invention discloses a medicine for treating rectal prolapsed, and a preparation method of the medicine. The medicine is mainly prepared from rhizoma cimicifugae, grifola, radix aucklandiae, semen pruni, radix dipsaci, pericarpium citri reticulatae, radix astragali seu hedysari, bighead atractylodes rhizome, fructus psoraleae, rhizoma coptidis, rhizoma alpiniae officinarum, fructus aurantii, radix saposhnikoviae, radix platycodi, radix gentianae macrophyllae, fructus cannabis, rhizoma alismatis, radix bupleuri, semen cuscutae, fructus rosae laevigatae, galla chinensis and radix sanguisorbae according to a certain weight ratio. The medicine has the functions of tonifying defensive qi and strengthening exterior, regulating qi-flowing for strengthening spleen, preventing rectocele and promoting generation of body fluid, eliminating dampness and reducing phlegm, reinforcing vital energy and astringing intestine to stop diarrhea, and is quick in response, good in curative effect and relapse-free when being used for treating the rectal prolapsed.