The invention discloses a preparation method of a hydrocarbon fuel. The method comprises the following steps of: dissolving grease and a loaded ruthenium-based catalyst into an organic solvent in the presence of hydrogen; and undergoing a hydrodeoxygenation reaction on the grease in an enclosed reaction container to obtain the hydrocarbon fuel, wherein TiO2 is taken as a catalyst carrier in the loaded ruthenium-based catalyst. Compared with the prior art, the method has the advantages that: the loaded ruthenium-based catalyst in which the TiO2 is taken as the catalyst carrier has high catalytic action; and under the synergic action of ruthenium and the carrier TiO2, the reaction temperature of the hydrodeoxygenation reaction of the grease is lowered, the hydrodeoxygenation reaction of the grease is realized under a relatively mild condition, the transformation of alcohol serving as an intermediate product is promoted, and the yield of the hydrocarbon fuel is further increased. As proved by an experimental result, the reaction temperature of the preparation method provided by the invention is 200-250 DEG C, and the yield of the hydrocarbon fuel is over 90 percent.