The silica modified CeO2 gas sensing nanomaterials are synthesized using a sol-hydrothermal route. The 8%silica-CeO2 has larger specific surface areas of 83.75 m2/g and smaller crystalline size of 11.5 nm than pure CeO2, respectively. Compared to pure CeO2, the 8%silica-CeO2 based gas sensor exhibits significant enhancement NH3 gas-sensing performance. At room temperature, it shows much better gas response of 3244% to 80 ppm of NH3 gas and lower detection limit (0.5 ppm) towards NH3 gas. It is also found that the gas response of the NH3 gas sensors increases linearly with the increase of NH3 gas concentration. Moreover, the NH3 gas sensor have good reversibility, stability and selectivity. The reason of enhanced NH3 gas-sensing performance is not only because of the increased specific surface areas, but also due to the electrolytic conductivity of NH4+ and OH− on the surface.