A 50 μm thickness polyimide (PI) film was implanted with 120 keV nitrogen ion to doses of 5 10 1 4 ions cm - 2 and 5 10 1 6 ions cm - 2 . The structure of the treated PI was characterized by X-ray photoelectron spectroscopy (XPS) and reflecting FT-IR, whereas the friction and wear behaviors of both implanted and unimplanted PI were investigated using a one-way reciprocating friction tester against a steel ball.Results indicate that nitrogen ion implantation decreases friction coefficient as well as wear rate, especially for the dose of 5 10 1 6 ions cm - 2 . XPS and FT-IR analyses suggest the formation of cross-linking with CN bond during the process of nitrogen ion implantation.