In this work, carbon fibers were sized with different plasticizer of sizing agent in order to improve the performances of carbon fibers and the interface of carbon fibers composites. The chemical and physical changes induced by the treatments on carbon fibers surface are examined using dynamic contact angle analysis test(DCAT) , X-ray photoelectron spectroscopy (XPS). The interfacial shear strength (IFSS) of CF/EP composites are analysised by micro-droplet test. At the same time, the wear resistance was also studied in order to understand the effect of the plasticizer of sizing agent on the carbon fibers. The study shows that the 3# sized carbon fiber has the better wetting and surface energy. XPS results reveal that the 3# samples show a significant increase in oxygen-containing groups, such as–C–OH, -COOH, -C–O–C- and -COOR. 3#sizing agent also show better interface adhesion between fibers and matrix and has better wear resistant properties.