The work aims to improve the gas-sensitivity properties of WO3 based coatings. Au-WO3 composite coating was prepared by plasma spraying technology with mixed feedstock suspensions containing a precursor as WCl6 and a certain ratio of nano-Au. SEM, EDS and XRD were used to characterize the microstructures of Au-WO3 composite coating. The gas-sensitivity properties of prepared Au-WO3 composite coating were studied by a self-made gas-sensitivity test system and the gas sensitivity mechanism was researched. During the suspension plasma spraying, the solvent of the precursor droplets was evaporated and then the nucleation, crystallization and growth of WO3 occurred. Then, the formed WO3 solid particles were melted or semi-melted, and accelerated to impact the surface of the substrate to form a coating. The effects of the spraying distance on the crystallinity and morphology of the WO3 coatings were significant under the same conditions. A coating with integrity crystal and fine grains (20~50 nm) was obtained at the spraying distance of 170 mm which was conductive to gas-sensitivity properties. The gas-sensi?tive properties of the Au-WO3 composite coating were significantly better than that of the pure WO3 coatings. A schottky junction formed at the interface of Au and WO3 improves the gas-sensitive properties of composite coating and leads to a reduction in conductivity of the composite coating. Therefore, the height of the contact barrier increases and initial resistance becomes large.