Acrylic acid was graft-copolymerised onto Rhi. oryzae's cell wall structural polysaccharide directly and efficiently in aqueous solution with eerie ammonium nitrate as initiator. The maximal grafting percentage of 135.5% was obtained under the condition of [Ce4+] = 5 mmol.L-1, [AA] = 1 mol.L-1, T = 60 degreesC and t = 3 h. Graft copolymerization was suggested to proceed through free radical reaction mechanism. Grafting occurred primarily on chitosan. Acrylic acid was also attempted to be grafted onto Asp. niger cell wall structural polysaccharide, and only 44.2% of grafting percentage was resulted.