Grafting of methyl methacrylate(MMA)onto microcrystalline cellulose(MCC)using ceric ammonium nitrate(CAN)as a redox initiator was carried out under ultrasound and microwave synergistic irradiation.The effects of varying monomer concentration，initiator，and reaction time of graft polymerization were studied by determining the grafting parameters，such as grafting percentage.The optimized reaction conditions which resulted in maximum graft ratio of 93% were monomer concentration of 3 ml·（g MCC）-1，initiator concentration of 0.25 mmol·（g MCC）-1 and exposure time of 9 min.The graft copolymers were characterized by Fourier transform infrared spectroscopy(FTIR)，X-ray diffraction(XRD)，thermo gravimetric analysis(TGA)，and differential scanning calorimeters(DSC)，which elucidated the structure changes in comparison with MCC.The crystallinity of the graft copolymers decreased in comparison with that of MCC，and TGA and DSC revealed that copolymer had more thermal stability.