We prepared the polystyrene/graphene oxide core-shell microspheres (PS/GO) based on the self-assembly between graphene oxide sheet (GO) and cationic polystyrene microspheres (PS) through electrostatic and π-π attraction between them and the PS/GO were reduced by hydroiodic acid (HI) to obtain the polystyrene/reduced graphene oxide core-shell microspheres (PS/rGO), which were characterized byXRD, SEM and TEM. It was found that the thickness of shell GO was influenced by ultrasonic and mechanical stirring, self-assembly time and GO concentration. The PS/rGO composites with different amount of shell rGO were characterized by conductivity and thermal stability measurements and the results show that the shell rGO will directly affect its conductivity and thermal properties. Besides, the conductivity and thermal stability of PS/rGO were improved compared to PS due to the special core-shell structure: the electronic resistance of PS (17.3 Ω) were down to 8.34 Ω (PS/rGO) and the initial thermal decomposition temperature of PS/rGO were increased by nearly 120 ℃.