The invention relates to a synthesis method of a phosphoric acid bridged and compounded TiO2-BiVO4 nanometer photocatalyst, and particularly relates to a synthesis method of a photocatalyst and the method is used for solving the technical problem of poor activity for decomposing bismuth vanadate under irradiation of visible light to produce hydrogen in water. The method comprises the following steps of: firstly, preparing phosphoric acid modified bismuth vanadate; secondly, preparing a solution A; thirdly, preparing a solution B; fourthly, preparing titanium dioxide compound phosphoric acid bridged bismuth vanadate; and fifthly, dispersing the titanium dioxide compound phosphoric acid bridged bismuth vanadate into distilled water, adding chloroplatinic acid, stirring under the irradiation of a xenon lamp with the power of 300w, cleaning, drying and grinding to obtain the phosphoric acid bridged and compounded TiO2-BiVO4 nanometer photocatalyst. Compared with pure bismuth vanadate, the phosphoric acid bridged and compounded TiO2-BiVO4 nanometer photocatalyst provided by the invention has the advantages that the service life of a carrier of the phosphoric acid bridged and compounded TiO2-BiVO4 nanometer photocatalyst is prolonged by 1ms, and the separation efficiency of the carrier is increased by 1.5 times. The phosphoric acid bridged and compounded TiO2-BiVO4 nanometer photocatalyst has high activity for decomposing under the irradiation of the visible light to produce the hydrogen in water.