Abstarct: Gas sensors are devices that can convert the concentration of an analyte gas into an electronic signal. Tin oxide (SnO2) is an important n-type mextal oxide semiconductor which has been utilized as sensor for several decades. In recent years, there have been extensive investigations of nanoscale semiconductor gas sensors. The size reduction of SnO2 sensors to nanometer scale provides a good opportunity to dramatically increase their sensing properties in comparison with their macroscale counterparts. In this work, two kinds of SnO2 nanostructures (nanowires and nanorods) were studied. SnO2 nanowires were synthesized by CVD methodon Alumina, ITO, Quartz and Si (1,0,0) substrates. SnO2 nanowires with different diameters were obtained. However, the aspect ratio (length/width) of nanorods was significantly smaller than that of nanowires. Both nanowires and nanorods were characterized scanning electron microscopy, Transmission electron microscopy,X-ray diffractionand Photoluminescence spectroscopy. The sensing performance of the synthetic SnO2 nanostructures were investigated by two gases: ethanol vapourand LPG. Both SnO2 nanostructures showed good sensitivity and selectivity to ethanol vapour. At high temperature, the SnO2 nanosensors were more responsive to LPG. Due to the size dependence, SnO2 nanowires with the smallest diameter is considered the best sensor candidate among SnO2 nanowires.