WO3 nanoplates are synthesized by a hydrothermal method. Morphology and structure of the WO3 nanoplates are analyzed by SEM and XRD. Gas sensing properties of the as-prepared WO3 sensor are investigated by a static gas-sensing system. The results show the WO3 nanoplates demonstrate 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 a gas sensor for ethanol detection.