PC/ABS/GO composites were fabricated using a twin screw extruder in order to study GO dispersion and the physical properties of polycarbonate (PC)/acrylonitrile-butadiene-styrene copolymer (ABS)/graphene oxide (GO) composites depending on fabrication methods. The position of the GO was thermodynamically identified by measurement of contact angle and the use of wetting coefficient. The GO tended to be located in the ABS phase and ABS-g-MA. In TEM images, most of the GO was located in the ABS phase regardless of fabrication methods. In comparisons of tensile strength and Izod impact strength, the physical properties of PC-GO/ABS composites using PC/GO composites were significantly improved. 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 SEM and TEM images, it was confirmed that GOs were mostly dispersed in the PC and ABS interface due to the short residence time in the extruder as screw rpm rose.