The invention discloses a medicine for treating gingivitis caused by kidney yin deficiency and a preparation method of the medicine. The medicine is prepared from the following medicinal materials: radix rehmanniae praeparata, stellaria neglecta weihe, polygonum multiflorum, manyflower supplejack stem and leaf, fructus broussonetiae, turbinate aster, dendrobe, polygonum polystachyum, polygonatum kingianum, freshwater snail's operculum, wolfberry fruit, eclipta, loropetalum chinense, glossy privet fruit, agilawood, mulberry, radix ophiopogonis, angelica sinensis, buckwheat straw, codonopsis pilosula, dwarf lilyturf, human placenta, semen cuscutae, physalis angulata, eucommia ulmoides, pandanus tectorius soland, platycladi seed, metaplexis fruit, ganoderma lucidum, chinese elder, acorus tatarinowii, pennycress seed, manyprickle acanthopanax root and deer's thyroid gland. The medicine has the beneficial effects that the medicine has the effect of nourishing kidney yin and is mainly used for treating gingivitis caused by kidney yin deficiency; by virtue of the theory of the traditional Chinese medicine, on the basis of the integer concept, treatment based on syndrome differentiation is carried out by regulating dynamic balance of qi and blood, yin and yang and integral organs of the organism and internal environments of the integral organs; multi-target specific treatment is carried out; and the medicine has the advantages of being fast in acting, high in effective rate, accurate in curative effect, short in treatment course, free of a toxic or side effect and low in proce.