In this work, pure and 1-5 mol% Co-doped SnO₂nanofibers were synthesized via an electrospinning method. The morphological and microstructural properties of these nanofibers were obviously changed and the grain size of the SnO₂nanocrystal were greatly decreased by Co doping. Sensors based on these nanofibers were fabricated after a hot pressing process on the ceramic plates. The gas-sensing properties of pure and Co-doped SnO₂nanofibers were tested to several kinds of Volatile Organic Compounds (VOCs). The results indicated that among all the samples (0, 1, 3 and 5 mol% Co-doped SnO₂nanofibers), 3 mol% Co-doped SnO₂nanofibers showed the highest response toward 100 ppm ethanol, having a response of 40.1, which was over 4 times higher than pure SnO₂nanofibers. At the same time, the sensors based on 3 mol% Co-doped SnO₂nanofibers also exhibited good repeatability and long term stability, which were promising for designing ethanol gas sensor with high performance.