Polymerization of methyl methacrylate was carried out in the presence of 2-cyanoprop-2-yl 1-dithionaphthalate (CPDN). The results exhibit controlled polymerization characters: well-controlled molecular weight, narrow polydispersity (minimal value: 1.09), molecular weight linearly increasing with conversion and first-order kinetics of polymerization. The polymer can be used to synthesize methyl methacrylate-styrene copolymer with narrow polydispersity (minimal value: 1.22). The polymers were characterized by H-1 NMR and GPC. The effect of molar ratio among MMA/CNDB/AIBN on polymerization was investigated.