Emulsion type sizing agent for carbon fiber was synthesized using epoxy resin (E-51) and epoxidized polybutadiene (EPB) by adding emulsifiers and other additives. Standing stabilization of sizing agents was analyzed. Meanwhile, abrasion resistance, fluffs and breakage, stiffness were used to analyze the processability of carbon fiber. The effect of sizing agents on interfacial adhesion of carbon fiber/resin composites was estimated by interlaminar shear strength (ILSS). The results showed that the sizing agent could significantly improve processability of carbon fiber due to the increase of abrasion resistance and reduce of fluffs and breakage. By adding EPB in sizing agent and adjusting the ratio to E-51, the flexibility of carbon fiber was ameliorated and the sizing agent could adapt to various resin matrices. Compared to the desized carbon fiber reinforced composite, ILSS of sized carbon fiber/epoxy resin composite was increased by 16.9%, and ILSS of sized carbon fiber/vinyl ester resin composite was enhanced by 19.1%.