In this article, the graft copolymerization of methy methacrylate with canna-starch under the initiating of manganic pyrophosphate was investigated systemly. It was found that the percentage of grafting, grafting efficiency, and rate of grafting were all dependent, to some extent, on the concentration of the initiator, monomer and starch, as well as reaction time and temperature. The rate equation of graft copolymerization established from the experimental results was similar to the equation derived from the reaction mechanism. The graft copolymer was investigated with an infered spectroscope, scanning electron microscope, and x-diffraction methods.