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 Tg of PS doesn’t change with the blend composition

and Tg 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 Tg of PC results from PS interpenetrating into the phase of PC

and no change in Tg 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-gGMA(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 Tg 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．