A flocculant was synthesized by graft copolymerization of acrylamide onto konjac glucommannan using potassium permanganate/thiourea redox system as an initiator. The effects of the concentration of monomer, initiator, H2SO4, as well as reaction time and temperature on the graft copolymerization were studied. The optimum synthesis conditions were: the concentrations of acrylamide, KMnO4 and H2SO4 were 2.0 mol.L-1, 20 mmol.L(-1)and 3.0 mmol.L-1, respectively, and the molar ratio of KMnO4/thiourea was 2/1 at 60 C for 3 h. Compared with polyacrylamide, the graft copolymer had better flocculating effect on the kaolin suspensions, as well as the local Qinjiang river water and the machine water in paper making.