Mechanism of graft copolymerization of methyl methacrylate onto model compound for chitosan with Ce4+ion was investigated by means of kinetics measurement and oxidation product analysis in addtion to polymer molecule weight analysis. The kinetic feature and product structure analysis of Ce4+ oxidation of model compound for chitosan showed that chelate complex at adjacent hydroxylamine functional group was involved and then disproportionated to radical. The results from GPC suggested that one adjacent hydroxylamine group formed the sole initial radical at 40℃ or two initial radicals at 90℃.