Gas sensors have become increasingly significant because of the rapid development in electronic devices that are applied in detecting noxious gases. Adjusting the crystal phase structure of sensing materials can optimize the band gap and oxygen-adsorptive capacity, which influences the gas sensing characteristics. Therefore, titanium dioxide (TiO2) materials with different crystal phase structures including rutile TiO2 nanorods (R-TiO2 NRs), anatase TiO2 nanoparticles (A-TiO2 NRs) and brookite TiO2 nanorods (B-TiO2 NRs) were synthesized successfully via one-step hydrothermal process, respectively. The gas sensing characteristics were also investigated systematically. The sensors based on R-TiO2 NRs displayed the higher response value (12.3) to 100 ppm acetone vapor at 320 °C compared to A-TiO2 NRs (4.1) and B-TiO2 NRs (2.3). Furthermore, gas sensors based on R-TiO2 NRs exhibited excellent repeatability under six cycles and good selectivity to acetone. The outstanding sensing properties of gas sensors based on R-TiO2 NRs can be ascribed to relatively narrow band gap and more oxygen vacancies of rutile phase, which showed a probable way for design gas sensors based on metal oxide semiconductors with remarkable gas sensing performances by the crystal phase adjustment engineering in the future.