SnO2/Au-doped In2O3 core-shell (CS) nanofibers (NFs) were designed and synthesized through a facile coaxial electrospinning method. To investigate its potential application, commercial gas sensor was fabricated and its gas sensing properties were tested. The SnO2/Au-doped In2O3 CS NFs sensor showed enhanced acetone gas sensing properties compared to the Au-doped In2O3single NFs sensor counterpart. The SnO2/Au-doped In2O3CS NFs sensor exhibited a high response to acetone at 300 °C, whereas Au-doped In2O3 NFs sensor showed a relative low response to acetone at 300 °C. Furthermore, the former sensors also showed a fast response speed and a good selectivity to acetone. In addition, the underlying mechanism for the enhanced acetone sensing properties of SnO2/Au-doped In2O3CS NFs sensor could be attributed to the catalytic activity of Au and the CS structure. The approach and results proposed in this study may contribute to the realization of more sensitive CS structure NFs sensors.