The invention discloses a cigarette harm reduction additive, which comprises a plant extract composition, wherein the plant extract composition comprises licorice flavonoids, folium ginkgo extracts, epimedium flavonoids and astragaloside, the addition proportion of tobacco shreds into the additive is 0.001 to 0.05 weight percent, the additive comprises 15 to 84 weight percent of licorice flavonoids, 15 to 84 weight percent of folium ginkgo extracts, 0.3 to 20 weight percent of epimedium flavonoids and 0.5 to 25 precent wt of astragaloside and can further comprise plant extracts of total saponin from ophiopogon japonicus. The additive can externally inhibit the generation of harmful smoke substances such as polycyclic aromatic hydrocarbon, free radicals and the like, so the harm of smoke to people is effectively reduced. In addition, the invention also provides the preparation method of the cigarette harm reduction additive.