Porous Ce0.94Zr0.06O2 nano-sheets sensing material was synthesized using a facile sol-hydrothermal process. The average thickness of the Ce0.94Zr0.06O2 nano-sheets was about 8 nm, and the nano-sheets were found to have a mesoporous structure with an average pore size around 2.1 nm. The mesoporous structure of Ce0.94Zr0.06O2 nano-sheets resulted in larger specific surface areas of 185.4 m2/g and more pore volumes of 0.51 cm3/g than those of CeO2, which was beneficial to the absorption of target gas. Due to the special mesoporous structures in the nano-sheets and the plenty of hydroxyl groups on the surface, the NH3 sensors made of the porous Ce0.94Zr0.06O2 nano-sheets showed a higher sensitivity (87–100 ppm NH3) and a lower detection limit (100 ppb) at room temperature than the sensors made of pure CeO2 nano-sheets prepared using the similar process. And they exhibited good selectivity, reproducibility and long-term stability to NH3 detection at room temperature.