Xylene is a volatile organic compound which is harmful to the human health and requires precise detection. The detection of xylene by an oxide semiconductor gas sensor is an important research direction. In this work, Co3O4 decorated flower-like SnO2 nanorods (SnO2/Co3O4 NRs) were synthesized by a simple and effective two-step method. The SnO2/Co3O4 NRs show high xylene response (R g/R a = 47.8 for 100 ppm) and selectivity at the operating temperature of 280 °C, and exhibit high stability in continuous testing. The resulting SnO2/Co3O4 NRs nanocomposites show superior sensing performance towards xylene in comparison with pure SnO2 nanorods. The remarkable enhancement in the gas-sensing properties of SnO2/Co3O4 NRs are attributed to larger specific surface area and the formation of p-n heterojunction between Co3O4 and SnO2. These results demonstrate that particular nanostructures and synergistic effect of SnO2 and Co3O4 enable gas sensors to selectively detect xylene.