The purposes of this thesis is to study on the GO dispersion of polycarbonate/graphene oxide (GO) composites. PC/GO composites were prepared by using a twin screw extruder at 240, 260, and 280 ℃ after solution mixing with chloroform, and then chemical reactions between PC and GO were investigated. The chemical reaction degree of PC/GO composites with GO reduction time was confirmed by C-H stretching peak at 3000 cm-1 and the chemical reaction degree decreased with GO reduction time. The scanning electron microscope (SEM) photos were not proper method for measuring the GO dispersion of PC/GO composites because the textures confined to minor regions and were not clear. The rheological properties is one of the methods measuring the inorganic filler dispersion of polymer composites. The slope for storage (G’)-loss (G") modulus plot decrease with an increase in heterogeneous property of the polymer melts. So we can check the GO dispersion of the PC/GO composites using by the slop for G’-G” plot. According to the G’-G" slopes for PC/GO composite with reduction time, GO was well dispersed within PC matrix when the reduction time decreased. It was re-confirmed by atomic force microscope (AFM) results. Based on the degradation temperature by TGA, the G’-G” slopes, and surface roughness by AFM, the branched PC was better than linear PC for the GO dispersion. The fact was confirmed by stress-strain curve that the Young’s modulus increased with the improvement of GO dispersion. In order to check the effect of manufacturing method on the GO dispersion, three methods were tried. First is in-situ PC polymerization with GO and second is in-situ PC polymerization with modified GO-COCl. The final PC/GO composites were fabricated by a twin-screw extruder at 260 ℃ using the above two synthesized PC/GOs. The G’-G" slop and AFM results showed that the GO of in-situ PC/GO composite was well dispersed than that of in-situ PC/GO-COCl composite.