Polymers bearing a single formoxyl acrylic group at the chain end were synthesized by reacting between poly(styryl)lithium and maleic anhydride（MAH）. The functionalized polymer was characterized by GPC, IR and Raman. The end-capping mechanism was figured, including the possible coupling reaction of dimmer. According to kinetic study, the reaction behavior could be explained by SN2 mechanism. Specifically, various factors related to functionalized efficiency, such as temperature, time of end-capping reaction, MAH/PSLi molar ratio (cMAH/cPSLi) etc., were investigated. The result has shown that the reaction efficiency was obviously affected by reaction time and polar addition. The functionalized efficiency at the optimism conditions can be up to 83.3%.