Abstract: In order to improve the shear property and water endurance of CFRP, the adhesion and the shear failure of epoxy resin reinforced by electrodeposited carbon fiber were investigated and the mechanism of eiec-trodeposition was discussed.Specimens of epoxy resin reinforced unidirectionally by electrodepo-sited carbon fiber have been tested. The results are shown in tables 1 and 2. It is obvious that the interlaminar shear strength of specimens reinforced by the treated fiber is enhanced up to 1000kg/cm2. It is worth notice that there are no losses in other mechanical properties, especially in impact strength with enhancement of ILSS.The electrodeposition mechanism on carbon fiber was investigated by means of IR and NMR （Figs 4 and 5）. The observation of the electrode-posited layer on fiber with SEM and ESCA（Fig. 6） demonstrated that the layer covered the fiber uniformly, compactly and completely, even entered tiny holes and grooves on the fiber surface. As the interface between fiber and deposited layer is a key problem due to the reaction of large number of carboxyl groups on the deposited layer with epoxy resin matrix, it displays interface adhesion fully with "anchor" effect, transfers the stress at the interface effectively, changes the formation and the development of cracks and confines the way of water penetration. The tailoring of the electrodeposited interlayer turnsathe simple shear failure at the interface into a complex failure mode, which enhances a series of mechanical properties such as shear strength, water endurance, impact strength and others.