Pure　tetragonal　and　monoclinic　phases　BiVO(4)　were　prepared　from　aqueous　Bi　(NO(3))(3)　and　NaVO(3)　solutions　by　a　rapid　microwave-assisted　method　that　employed　accurate　controlling　of　microwave　irradiation　time　and　power.　The　highly　crystalline　phase　converted　irreversibly　from　tetragonal　to　monoclinic　BiVO(4)　with　gradually　elongated　irradiation　time　gradually,　which　is　further　proved　by　X-ray　diffraction,　UV-vis　and　Raman　measurements.　These　variations　of　phase　structures　led　to　different　photocatalytic　properties　under　visible　light.