Herein, large-scale uniform flowerlike SnO 2 bundles that built by numerous one-dimensional tetragonal prism nanorods were synthesized by a simple hydrothermal method with the help of the poly(ethylene glycol) (PEG). Further investigation of the formation mechanism reveals that the PEG-assisted hydrothermal process is vital to the formation of the better complex nanostructures. The sensors fabricated from the flowerlike SnO 2 nanorods bundles exhibited the sensitivity of 12.4 for 50ppm of ethanol at reduced working temperature (300°C). Moreover, a linear dependence of the sensitivity on the ethanol concentration was observed, which suggests that the flowerlike SnO 2 nanorods bundles are very suitable to detect ethanol with low concentration.