Sinopodophyllum emodi is a herbaceous perennial plant. It is used in the treatment of hemopathy, retained placenta and lochiorrhea. Its root contains podophyllotoxin, which has an anti-tumor effect. Compounds were isolated by column chromatography, and were analyzed by NMR chromatography; flow cytometry was used to determine the anticancer activity of ethanol extract of Sinopodophyllum emodi. The ethanol extract was subjected to column chromatography, and the isolated compounds were structurally identified by H-NMR and C-NMR techniques, three compounds were obtained from Sinopodophyllum emodi, namely podophyllotoxin, podophyllotoxone and 4'-demethyl podophyllotoxin; after 48 h action of Sinopodophyllum emodi ethanol extracts in each treatment group on K562 cells, they produced very significant effects on cell cycle distribution. The proportions of G0/G1 and S phase cells decreased, while the proportion of G2/M phase cells increased, all in an apparent dose dependent manner, indicating that the ethanol extract of Sinopodophyllum emodi arrested K562 cell cycle at the G2/M phase. Sinopodophyllum emodi ethanol extract can inhibit the proliferation of K562 cells.