WO3 nanoplates were synthesized by a hydrothermal method. Morphology and structure of the WO3 nanoplates were analyzed by SEM and XRD, respectively. Gas sensing properties of the as-prepared WO3 sensor were investigated by a static gas-sensing system. The results show that the WO3 nanoplates reveal good crystallinity with mean edge length of 200∼300 nm and wall thickness of about 50 nm. The optimal operating temperature of the WO3 sensors is 300 °C. At this operating temperature, the WO3 sensor exhibits ultra-fast response (2∼4 s) and fast recovery time (4∼16 s) for ethanol detection, and high selectivity to other gases such as methanol, benzene, dichloromethane and hexane, which indicates its excellent potential application as the gas sensor for ethanol detection.