Abstract: Objective To isolate compound Paris saponin Ⅱ(PSⅡ) from Rhizoma Paridis and observe its antitumor activity. Methods PSⅡ was isolated and determined by electrospray ionization-mass spectrometry,¹H and ¹³C nuclear magnetic resonance spectral analysis. PSⅡ was used to treat cancer cells to analyze the toxicity and relative time-and dose-dependent manner. Apoptosis of cells were investigated by flow cytometry and TUNEL assay. Western blotting was used to analyze the effects of PSⅡ to MAPKs and mitochondrial apoptotic pathway. Results The anti-tumor activities of PSⅡ on ovarian carcinoma cell line SKOV3 were investigated. The IC₅₀ of PSⅡ to SKOV3 was 4.81 μmol/L. Increased apoptosis rate in a dose-and time-dependent manner was observed by Flow cytometry and TUNEL. The activity of ERK1/2 was inhibited by PSⅡ and increased expression of cytochrone c, caspase-3 and caspase-9 was also noticed after the treatment of PSⅡ. Conclusion PSⅡ can inhibit the growth of ovarian cancer cells SKOV3 through affecting the key proteins on MAPKs pathway and inhibiting the activity of ERK1/2 and eventually eliciting programmed cell death of SKOV3. The mitochondrial apoptotic pathway may be involved in the PSⅡ induced apoptosis.