To study the in vitro effect of herb components on scavenging harmful components of cigarette smoke such as radicals, polycyclic aromatic hydrocarbons, nitrosamines in vitro, and its reducing effect on cytotoxicity of cigarette smoke.spectrophotometry was used to examine the scavenging effect of herb components on DPPH free radicals, superoxide anion radical, and hydroxyl radical, and the results were compared with the anti-oxidation of ascorbic acid. Fluorescence spectroscopy was used to examine the scavenging effect of herb components on polycyclic aromatic hydrocarbons. UV spectrophotometry was used to examine the scavenging effect of herb components on volatile nitrosamines. MTT assay was used to examine cytotoxicity of cigarette smoke.All the herb components showed a certain scavenging effect on DPPH free radicals, superoxide anion radical, hydroxyl radical, polycyclic aromatic hydrocarbons and volatile nitrosamines, espacially the ginkgo biloba extract (GBE), flavonoids of glycyrrhiza, procyanidine, total saponins in ophiopogonin, total saponins of astragalus and epimediun flavonoids. After these six herb components were added to cigarette, the cytotoxicity of cigarette smoke on BEP2D cells was remarkably reduced, by increasing cell survival fraction (SF, %) and mean lethal dose (DML).The herb components can scavenge harmful components of cigarette smoke such as radicals, polycyclic aromatic hydrocarbons and nitrosamines, which reduce the damage of cigarette smoke on human being.