Horseshoe-shaped SnO₂with annulus-like mesoporous was successfully synthesized by self-assembly method in this work. The obtained materials were characterized by X-ray diffraction (XRD), Brunauer-Emmet-Teller (BET), Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results revealed that the horseshoe-shaped samples were composed of amounts of annulus like mesoporous with an average diameter about 2 nm and high specific surface area. Moreover, gas sensor based on the as-prepared samples was fabricated and its sensing performances were investigated. It was revealed that the sensitivity towards 100 ppm of ethanol enhanced to 17.3 under the operation temperature 225℃ for the sensor based on SnO₂calcined at 400 ℃. And the sensor based on SnO₂calcined at 400 ℃ presented a higher response towards 10-200 ppm ethanol. In addition, the relationship between morphology and sensing property of synthesized materials towards ethanol has been investigated. The results above indicate the potential of the annulus-like mesoporous SnO₂as ethanol gas sensor material.