Abstract: An emulsion made by mixing carbon nanotubes(CNTs), epoxy, Tween-80 and Span-60 was used as a sizing agent of carbon fibers(CFs) used to prepare CF/bisphenol A epoxy composites. The effects of the CNT modification on the stability of the emulsion, surface morphology and composition of the CFs, the contact angle of bisphenolA epoxy on the CFs and the interfacial shear strength of the composites were investigated by SEM, XPS, AFM and mechanical tests. Results indicate that the stability of the CNT-modified emulsion against sedimentationis better than the unmodified one. The surface roughness of the CFs is increased by 73.1%, the contact angle is reduced by 11.9%, and the number of surface oxygen functional groups on the CFs is increased by 45.96% compared with those without CNT modification. The interfacial shear strength of the composite with an optimized CNT content of 0.75 wt% is 14.7% higher than that without CNTs.