A vinyl monomer having tertiary aromatic amino-groups，4-N，N-dimethylaminosty-rene (DMAS) has been synthesized from 4-N，N-dimethylaminobenzaldehyde with mal-onie acid by knoevenagel reaction and then decarboxylated．Although the DMlAS bardly proceeds the radieal polymerization initiated with or-ganic peroxide such as BPO

LPO，bet it was found that DMA8 under lower concentra-tion would form redox system with BPO to initiate the polymerization of some vinyl monomers such as MMA readily．The rate equation of the polymerization of MMA ini-tiated by DMAS-BPO system is given as Rp=Kp [MMA][DMAS]0.5 [BPO]0.5 The rate constants of the polymerization were determined at 30．40，50 and 60℃，and the overall activation energy was caleulated as low as 7.4 kcal／mol．The UV-analysis of the obtain-ed polymers confirmed that DMAS not only initiated the polymerization of MMA by combining with BPO，but also entered into the polymer chains．