The objective of this work is to improve the interlaminar shear strength (ILSS) of the composites by surface coating of carbon fibers (CFs). The effect of polypyrrole (PPy) coating on CF composites was studied. The morphologies of untreated and treated CFs were characterized by scanning electron microscope and x-ray photoelectron spectroscopy, respectively. Surface analysis showed that the surface of CFs chemisorbed oxygen-containing groups and active carbon as well as increased wettability after surface treatment with PPy. The mechanical properties show that the treated CF composites can possess excellent interfacial properties with polytetrafluoroethylene matrix, and ILSS of the composites is up to 106 MPa.