Surface treatments of polyimide(PI)film were carried out with oxygen plasma. The effect of plasma treatment conditions such as time, pressure and power on the surface properties of PI film has been investigated. The neat effect of air, nitrogen, oxygen and argon were compared and the optimum treatment conditions were obtained. Analysis of PI film indicated that the oxygen content on the surface increased and there was obviously etching on the PI film surface. The wettability of PI film increased after oxygen plasma treatment. And the peel strength between PI film and copper foil enhanced.