Abstract: A new technique is proposed to simulate proton irradiation using plasma sheath acceleration. The hydrogen ions（H⁺）are produced in a vacuum chamber by inductance-coupled radio-frequency discharge. A high negative voltage is applied to samples on the target holder to produce H⁺ ion irradiation. The optical transmissivity, surface morphology, and chemical structure of Polyimide(Kapton) samples are determined by UV-VIS-NIR scanning spectrophotometer, AFM and XPS analyses, respectively. The results show that the transmissivity of the Kapton films decreases with the increase of the amplitude of the high voltage pulses and the irradiation time. The number of finger-like bulges firstly increases and then decreases, accompanied with chemical structure changes, including the bond breaking of the carbonyl and aromatic ether, ring opening of cyclic imide, and the formation of some new bonds and structures.