The polymerization mechanism of various vinyl monomers in the presence of aromatic tertiary amines has been studied. It was found that the mechanisms of different monomers are varied with the structures of monomers. Those monomers, such as methacrylic esters containing α-CH3 group on the double bond could be polymerized with aromatic tertiary amine in the absence of light, while the monomers without α-CH3 group, such as methyl acrylate, acrylonitrile etc. would polymerize only under light.The structural effects,both of the monomer and the amine,on the rate of photopolymerization were studied. The activities of monomers and amines may be arranged in the following order Monomer:AN>MA>VA>ST Amine:DMT>DMA>DMB>DNA It is revealed that both the electro-negative group on the double bond of monomer which acts as an acceptor and the electro-positive group on the nitrogen atom of amine which acts as a donor would effectively increase the rate of photopolymerization.