Mesoporous tin oxide(SnO_2/ with a high surface area of 147.5 m~2/g has been successfully synthesized via self-assembly process, combining the driven forces of water-evaporation and molecular interactions. Scanning electron microscope, X-ray diffraction, transmission electron micrograph, Fourier transform infrared and BrunauerEmmett-Teller were employed to analyze the morphology and crystal structure of the as-synthesized mesoporous materials. As a gas sensor, mesoporous SnO_2 shows impressive performances towards NOx gas with high selectivity and stability as well as ultra high sensitivity about 94.3 to 10 ppm NO_x gas at 300 ℃. The best response time of the sample S-500 is about 3.4 s to 10 ppm NO_x at 450℃. Mesoporous tin oxide (SnO 2 / with a high surface area of ​​147.5 m 2 / g has been synthesized via via self-assembly process, combining the driven forces of water-evaporation and molecular interactions. Scanning electron microscope, X-ray diffraction, transmission electron micrograph, Fourier transform infrared and BrunauerEmmett-Teller were employed to analyze the morphology and crystal structure of the as-synthesized mesoporous materials. As a gas sensor, mesoporous SnO 2 shows impressive plays towards NOx gas with high selectivity and stability as well as ultra high sensitivity about 94.3 to 10 ppm NO_x gas at 300 ° C. The best response time of the sample S-500 is about 3.4 s to 10 ppm NO x at 450 ° C.