The　fabrication　of　a　stable　poly(vinylpyrrolidone)/poly(urushiol)　multilayer　film　was　achieved　through　the　UV　irradiation　of　layer-by-layer　self-assembled　multilayer　film　consisting　of　poly(vinylpyrrolidone)　and　urushiol　monomer.　The　assembling　process,　the　driving　force　for　construction,　the　thickness　and　hardness,　and　the　morphological/structural　changes　of　the　multilayer　film　were　investigated　by　Fourier　transform　infrared　(FT-IR)　spectroscopy,　UV-vis　spectroscopy,　X-ray　reflectometry　(XRR),　and　atomic　force　microscopy　(AFM),　respectively.　The　structure　of　the　multilayer　film　changed　from　sandwich　to　semi-interpenetrating　networks　(s-IPN)　after　photopolymerization.　This　resulted　in　great　improvement　in　hardness　while　without　destroying　the　well-defined　layered　structure　of　the　film.　The　surface　of　the　multilayer　film　is　smooth　and　defect-free.　©　2009.