The polysaccharide was extracted from the ethanol-extracted debris of Abelmoschus manihot (L.) Medic flower by water extraction and alcohol precipitation method. The total sugar content and extraction rate were determined. The Abelmoschus manihot (L.) Medic polysaccharide (AMP) was obtained by purification through DEAE-52 column chromatography and monosaccharide composition of AMP were determined. The bioactivities including antioxidant activity in vitro, DNA protecting activity and hepatic cancer cell HepG2 growth inhibitory effect of AMP were investigated. The results showed that the extraction rate reached 13.47% and the content of total sugar was 97.43%. AMP was mainly composed of rhamnose, glucose, arabinose and fucose at a molar ratio of 1.44:5.44:1.00:5.37. The order of radicals scavenging capacities of AMP was O2－· > ABTS+· > ·OH > DPPH· > NO· , which suggested AMP had certain antioxidant activity in vitro. 8 g/L AMP had the best inhibition effect on DNA oxidative damage induced by H2O2 . The inhibitory ratio of HepG2 cell increased with the increase of AMP concentration ranging from 0.125 to 5.000 g/L, indicating that AMP had potential antitumor activity.