Abstract: To screen the effective antitumor components of Platycodon grandiflorum (Jacq.)A.DC. and Hedyotis diffusa Willd, total flavonoids and total saponins of Platycodon grandiflorum, total flavonoids and total anthraquinones of Hedyotis diffusa Willd were prepared, the content of total flavonoids was determined by sodium nitrite - aluminum nitrate colorimetric method, the content of total saponins was determined by vanillin assay, the content of total anthraquinones was determined by ultraviolet spectromter method, the inhibitory effects of four extracts on human lung cancer cells A549 were determined by methyl thiazolyl tetrazolium (MTT) assay. The results indicated that, contents of total flavonoids from Platycodon grandiflorum and Hedyotis diffusa Willd were 5.51% and 1.19%, content of total saponins from Platycodon grandiflorum was 1.71%，content of total anthraquinones from Hedyotis diffusa Willd was 7.81%。The inhibition rate of 0.04 mg/mL total saponins from Platycodon grandiflorum on human lung cancer cells A549 was 87.59%，the inhibition rate of 0.5 mg/mL total flavonoids from Platycodon grandiflorum was 89.16%，the inhibition rate of 1.2 mg/mL total anthraquinones from Hedyotis diffusa Willd was 34.76%，the inhibition rate of 0.3 mg/mL total flavonoids from Hedyotis diffusa Willd was 24.33%。Total flavonoids and saponins from Platycodon grandiflorum have strong antitumor activity，which provides some powerful reference for the development of related antitumor products.