Abstract: Two tungsten oxides (WO₃-500 and WO₃-900) were prepared at different calcination temperatures by using ammonium mettungstate as tungsten source. The physicochemical properties of WO₃ before and after Pt loading were systematically characterized by XRD, SEM, TEM, XPS, H₂-TPR, and NH₃-TPD. The influence of the crystallization degree of WO₃ on the hydrogenation of naphthalene was studied under low-temperature reaction conditions. Compared with the WO₃-900 support, WO₃-500 obtained by calcination at lower temperature exhibited a lower crystallization degree with a large amount of W⁵⁺ species, which resulted in strong interactions with Pt. The strong interaction between W species and Pt contributed to the high acidic strength. The Pt/WO₃-500 catalyst demonstrated excellent catalytic performance for naphthalene hydrogenation to decalin at low reaction temperature (70 ℃) with full conversion and 100% decalin selectivity. Under identical conditions, conversion and decalin selectivity were only 26.7% and 1.7% over the Pt/WO₃-900 catalyst. Combining the characteristics of the catalysts and their catalytic results, we revealed the promoting role of oxygen defects in WO₃-supported Pt catalysts in the hydrogenation of naphthalene to decalin, which will provide theoretical guidance for designing efficient WO₃-supported Pt catalysts for hydrogenation reactions.