Layered　niobate　(K4Nb6O17)　thin　films　were　firstly　synthesized　by　a　novel　polymerized　precursor　method　using　niobium　oxide　(Nb2O5)　powder　as　starting　material.　After　annealing　at　600　degrees　C　or　above,　the　nanostructured　K4Nb6O17　thin　films　with　(040)　preferred　orientation　were　successfully　produced.　XPS　measurement　showed　that　the　atomic　ratio　of　K:Nb:O　in　the　thin　film　was　4.08:5.99:16.77,　which　was　in.　good　accordance　with　the　stoichiometry　of　K4Nb6O17.　The　hydrogen　evolution　from　water　decomposition　showed　the　excellent　photocatalytic　properties　of　the　films.　The　Boltzmann　equation　was　applied　to　compute　the　time　course　of　the　hydrogen　evolution　and　it　indicated　that　the　crystallization　was　responsible　for　the　high　photocatalytic　performance.