The effect of oxygen-plasma treatment for Kevlar fibers on the interfacial adhesion and typical macro-properties of Kevlar fiber/bismaleimide composites was intensively studied. It is found that oxygen-plasma treatment significantly affects the interfacial adhesion by changing the chemistry and morphology of the surfaces of the fibers, and thus leading to improved interlaminar shear strength, water resistance and dielectric properties of the composites. However, the improvement is closely related to the treatment power and time. The best condition for treating Kevlar fiber is 70W for 5 min. Oxygenplasma treatment provides an effective technique for overcoming the poor interfacial adhesion of Kevlar fiber based composites, and thus showing great potential in fabricating high performance copper clad laminates. (C) 2010 Elsevier B. V. All rights reserved.