Bimetallic nanocrystals (NCs) have received a lot of attention due to its excellent catalytic performance. Here, PtRu NCs were successfully synthesized by ethylene glycol and used to modify flower-like WO3 which was prepared via a simple hydrothermal method. The morphology and structure of the as-synthesized materials were characterized, and the performance of the gas sensor based on PtRu NCs decorated WO3 was carefully studied. The gas sensing investigation showed that there was a significant improvement in response after PtRu NCs being introduced. Among all samples, the WO3 sample modified with 0.4 wt% PtRu NCs showed the highest response to xylene at 170 ◦C (Ra/Rg = 261), which is almost 75 times than that of pristine WO3. In addition, it also presented fast response speed (2 s), good selectivity to xylene and excellent repeatability. The possible sensitization mechanism was proposed, the improvement of sensing performance could be ascribed to the high catalytic ac tivity of PtRu NCs, and the regulation of depletion layer by Schottky barrier and heterojunction at the contact interface between WO3 and PtRu NCs. This work can be promising for rapid detection of xylene for environ mental protection at low temperature