Abstract: Objective:To prepare fractionated extracts from extraction of water chestnut shell by ethanol and study the effects of fractionated extracts on proliferation and apoptosis of tumor cell. Methods:The ethanol extract of water chestnut shell was divided into ethyl acetate extract and n-butanol extract by organic solvent extraction. The contents of flavonoids and polyphenols were determined. The CCK-8 method and flow cytometry were used to detect the inhibition of proliferation and the the effect of water chestnut shell extract on the apoptosis of tumor cells. Results:The contents of polyphenols and flavonoids in ethyl acetate extract were higher than that of n-butanol extract. The concentrations of 25,50,100,200,400 μg/mL extracts of two kinds all had inhibitory effects on the proliferation of Hep G2 cells and SGC-7901 cells. The highest inhibition rate was more than 60%,and the dose increased significantly. When the extract was used to treat tumor cells at 400 μg/mL for 24 h,the cells showed significant apoptosis. The apoptotic rates of hepatoma cells treated with ethyl acetate and n-butanol extracts were 45.57% and 33.34%;the apoptotic rates of gastric cancer cells treated with ethyl acetate and n-butanol extracts were 31.01% and 21.65%. Conclusion:The ethyl acetate extract of the water chestnut shell had strong effects on inhibiting the proliferation of tumor cells and promoting the apoptosis of tumor cells.