The reactive compatibilization of syndiotactic polystyrene (sPS)/oxazolinestyrene copolymer (RPS)/maleic anhydride grafted ethylene-propylene copolymer (EPR-MA) blends is investigated in this study. First, the miscibility of sPS/RPS blends is examined by thermal analysis. The cold crystallization peak (T-cc) moved toward higher temperature with increased PRS, and, concerning enthalpy relaxation behaviors, only a single enthalpy relation peak was found in all aged samples. These results indicate that the sPS/RPS blend is miscible along the various compositions and RPS can be used in the reactive compatibilization of sPS/RPS/EPR-MA blends. The reactive compatibilized sPS/RPS/EPR-MA blends showed finer morphology than sPS/EPR-MA physical blends and higher storage modulus (G') and complex viscosity (eta*) when RPS contents were increased. Moreover, the impact strength of sPS/RPS/EPR-MA increased significantly compared to sPS/EPR-MA blend, and SEM micrographs after impact testing show that the sPS/RPS/EPR-MA blend has better adhesion between the sPS matrix and the dispersed EPR-MA phase.