A photo-luminescent multilayer film based on Keggin-type polyoxometalate PMo 12O 3- 40 and transition metal complex tris(2,2-bipyridine) ruthenium [Ru(bpy) 3] 2+ was prepared by using layer-by-layer assembly(LBL). The formation of multilayer film was monitored by ultraviolet absorption spectra(UV). The absorption intensity of characteristic peaks increases with a four-layer cycle, indicating that the LBL assembly film grows linearly and reproducibly. The composition of the film was measured by X-ray photoelectron spectrum(XPS). The film exhibited photo-luminescence arising from π*-t 2g ligand-to-metal transition of Ru(bpy).