The synthesis of konjac glucomannan-graft-polyacrylamide (KGM-g-PAM) was carried out at 25 degrees C by gamma-irradiation under a N2 atmosphere. The effects of absorbed radiation dosage and monomer concentration on grafting yield and water absorbency were studied. The grafted copolymers were characterized using Fourier Transform Infrared(FTIR) spectroscopy, nuclear magnetic resonance (NMR), x-ray diffraction (XRD),thermogravimetric analysis (TGA) and gel permeation chromatography (GPC). The grafting yield was observed to increase with increasing absorbed dosage and monomer concentration. Compared with the original KGM, the grafted copolymers exhibited better thermal stability and water absorbency. The results suggest that gamma-irradiation is convenient and efficient for inducing graft copolymerization of KGM and acrylamide (AM).