Effect of the grafted ABS (ABS-g-MA) for contents on the polycarbonate/poly(acrylonitrile-butadiene-styrene) (ABS) blends and graphene oxide dispersion and physical properties of PC/ABS/GO composites according to fabrication methods and screw rpm were discussed. The ABS-g-MA was prepared by melting extrusion of ABS and maleic anhydride (MAH) using twin screw extruder. The PC/ABS/ABS-g-MA blends for ABS-g-MA contents were fabricated by using twin screw extruder. PC/ABS was set at the weight ratio of 70/30 for all samples. According to the thermal, rheological and impact properties of PC/ABS blends, 5 phr of compatibilizer was chosen as an optimum content for the PC/ABS/GO composites. PC/ABS/GO composites were fabricated by using a twin screw extruder in order to study GO dispersion and physical properties of polycarbonate (PC)/acrylonitrile-butadiene-styrene copolymer (ABS)/graphene oxide (GO) composites depending on fabrication methods. When PC/ABS/GO composites were fabricated, we considered screw rpm, insertion methods for GO and application of a compatibilizer as parameters. PC/ABS was set at the weight ratio of 70/30 and a compatibilizer was ABS-g-MA where maleic anhydride(MA) was grafted to ABS. GO was inserted by a direct method, PC/GO composites and ABS/GO composites. The position of thermodynamic GO was identified by measurement of a contact angle and use of the wetting coefficient, and GO tended to be located in the ABS phase and ABS-g-MA. In the TEM images, most of GO were located in the ABS phase regardless of fabrication methods. In the comparison of tensile strength with Izod impact strength, the physical properties of PC-GO/ABS composites using PC/GO composites were improved excellently then PC-GO/ABS/ABS-g-MA. In PC-GO/ABS composites produced by using PC/GO composites and changing screw rpm, tensile strength and impact strength slightly increased as screw rpm rose. In the SEM and TEM images, it was confirmed that GO were mostly dispersed in the PC and ABS interface due to short residence time in the extruder as screw rpm rose.