Under the hydrothermal synthesis,an organic?inorganic hybrid compound was prepared through the self?assembly process by using phosphomolybdic acid as a polyoxometallate (polyacid for short) building block and triphenylphosphine as an organic ligand.Its molecular formula was determined by X?ray single?crystal diffraction technique as H15{(PMo12O40)2[MoO4?(PPh3)4]2?[NaO3?(PPh3)3][(H2O?PPh3)3](compound 1),which is a novel inorganic?organic hybrid material formed by electrostatic interactions between [PMo12O40]3-,[MoO4?(PPh3)4]2-,[NaO3?(PPh3)3]5- and H2O?PPh3 building blocks.The IR spectrum,luminescence spectra and cyclic voltammetric characteristic curves of compound 1 were also tested,focusing on the photocatalytic degradation of methylene blue(MB).The good ability of compound 1 to degrade organic dyes was demonstrated by photodegradation analysis experiments.