Provided are a preparation formula and method of cigarette poison reducing liquid and a method for reducing tobacco toxicity. According to the formula, the cigarette poison reducing liquid comprises selfheal, sculellaria barbata, folium isatidis, groundsel, snakegourd peel, plantain herbs, sedum sarmentosum, folium eriobotryae, honeysuckle stems, dandelions, serrate rabdosia herbs, Chinese mesona herbs, cordate houttuynia, feverfew, liquorice, folium mori, capillary artemisia, fructus forsythiae, mints, vervain, air potatoes, cortex lycii radicis, momordica grosvenori, abrus cantoniensis hance, honeysuckle, buddleja officinalis, scaphium scaphigerum, fructus aristolochiae, eclipta, oroxylum indicum, borneol, polygonum cuspidatum, chrysanthemums, blackberrykiky rhizome, lucid ganoderma, radix ophiopogonis, scutellaria baicalensis, pueraria flowers, rhizoma cimicifugae, radix scrophulariae, almonds, platycodon grandiflorum, pogostemon cablin, flos farfarae, paniculate swallowwort roots, perilla stems, aster tataricus, schizonepeta, rhizoma atractylodis, radix sileris, manchurian wild ginger, wherein the part by weight of each component ranges from 1 part to 5 parts. The preparation method includes the steps of processing, decoction, fermentation and distillation concentration. The method for reducing the tobacco toxicity includes the steps of controlling cut tobacco humidity, atomizing the poison reducing liquid and fumigating cut tobaccos. According to the preparation formula and method of the cigarette poison reducing liquid and the method for reducing the tobacco toxicity, injuries to human bodies of tobaccos can be reduced comprehensively, health care is achieved on smokers, and harm to the passive smoking group is reduced.