The compatibitily and morphology of HIPS/PC and HIPS g GMA/PC blends were studied.The compatibility and morphology of HIPS/PC blends were characterized by DSC and SEM,respectively.The result of DSC shows that T g of PS doesn’t change with the blend composition,and T g of PC decreases with the increase in weight fraction of HIPS,which indicates that the PC/HIPS blend is a partially miscible system.Results of SEM indicate that the decrease in T g of PC results from PS interpenetrating into the phase of PC,and no change in T g of PS results from PC not interpenetrating into the phase of PS.The copolymer of HIPS g GMA was prepared by reactive grafting method.The IR spectrum shows that GMA is grafted on the chain of HIPS.The compatibility and morphology of HIPS g GMA(35)/PC(65) were studied by DSC and SEM.PC(65)/HIPS g GMA(35) blend exhibits reduced size of disperse phase,enhanced interface adhesion and lower T g of PC phase as compared with the PC(65)/HIPS(35) blend.It implies that HIPS g GMA is an effective compatibilizer of the HIPS/PC blend.