In order to improve the sensitivity of SnO2 to ethanol gas, the spherical SnO2 with a particle size of 0.25μm and uniform particle distribution was prepared by hydrothermal method without adding surfactants. The characterizations were conducted，and the results showed that the spherical SnO2 particles were stacked by fine grains with a grain size of 4nm, with a higher specific surface area of 232.2043m2/g than existing research results. The gas-sensing performance test results show that the spherical SnO2 has the best gas-sensing selectivity to ethanol, with an optimal working temperature of 300℃. When the ethanol concentration is 100ppm, the gas sensitivity of spherical SnO2 to ethanol is 48.28, with a response time of 4s and a recovery time of 15s. Even to low concentration ethanol of 2ppm, the sensitivity of the spherical SnO2 can reach 4.6, indicating excellent gas-sensing performance of the spherical SnO2. This study provides data reference for the research and development of high-performance gas sensors.