PMMA-PS-PMMA triblock copolymers were prepared lay the combination of an anionic mechanism with charge-transfer polymerization. Polystyrene with aromatic tertiary amino groups at both ends (PSba) was synthesized first by the reaction of a living polystyrene macrodianion with excess p-(dimethylamino)benzaldehyde; then, the PSba was constituted into a binary system with benzophenone (BP) to initiate the polymerization of methyl methacrylate (MMA) under UV irradiation. The intermediate and resulting block copolymers were characterized by GPC, IR, and H-1-NMR.