To fabricate high-performance polymer/clay nanocomposites, many efforts have been made on how to promote the complete exfoliation of clay in polymer matrix. Nevertheless, it is still unclear that how the topological structure of polymer chain influences the exfoliation of clay during annealing process. In this study, three types of polystyrene (PS) with linear, symmetric star and asymmetric star structure were synthesized; subsequently they were used to prepare PS/clay nanocomposites with two kinds of organic modified clays (OMC, with or without benzene group in its modifier molecules). Our results indicated that star PS (symmetric and asymmetric) could efficiently promote the exfoliation of OMC with benzene groups in its modifier. Moreover, the possible exfoliation mechanism for clay was discussed, which was attributed to the synergistic effect of PS topological structure and its attractive interaction with clay. Thus, our work provided useful guidelines to fabricate high-performnce polymer/clay nanocomposites and extend their applications.