Here, AuxRh1−x alloy nanocrystals (NCs) were used to decorate W18O49 for enhanced detection of n-butanol vapor. Monodisperse AuxRh1−x alloy NCs with a tunable composition and urchinlike W18O49 were synthesized by a simple solvothermal method. AuxRh1−x alloy NCs were loaded onto the W₁₈O₄₉surface by the impregnation method. A series of material characterization methods were employed to characterize the structure and morphology of as-synthesized materials. The performance of AuxRh1−x− W₁₈O₄₉-based sensors to n-butanol was investigated. The results demon strated that the Au₃₉Rh₆₁−W₁₈O₄₉-based sensor had the highest response, short response time, good selectivity, excellent repeatability, and stability to n butanol. The gas sensing mechanism was supposed, the excellent catalytic capability of the AuxRh1−x alloy NCs were believed to be a major factor in enhancing the detection of n-butanol.