Pt-loaded mesoporous WO₃was fabricated by nanocasting method. Mesoporous structure provided ordered tunnel which was convenient for gas diffusion and the large specific surface area which could offer more active sites. The noble metal (Pt) improved the catalytic efficiency which played crucial role in enhancing the performance of the gas sensor. The obtained materials were characterized by X-ray diffraction (XRD), Brunauer-Emmet-Teller (BET), Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Characterization indicated that the synthesized materials had ordered mesoporous structure with excellent crystallinity and the pore size was about 10.6 nm. Static test system was employed to measure ammonia sensing properties for the as-prepared samples. The sensor based on Pt-loaded WO₃presented higher sensitivity, quicker response-recovery rates, excellent repeatability and selectivity. It indicated that the Pt-loaded mesoporous WO₃was a potential ammonia gas sensor material.