The growth of nanopushpin-like In2O3 nanostructures was demonstrated on the silicon substrate by catalyst-free chemical vapor deposition method. Structural analysis revealed single-crystalline nature of the In2O3 nanopushpins with a cubic crystal structure. The hydrogen sensor made from the In2O3 nanopushpins showed swift response and excellent stability. The influence of operation temperature on the hydrogen gas sensing property of In2O3 nanostructures was also investigated. Our results reveal that the sensor response of In2O3 nanopushpins increases with increasing the operation temperature.