High sensitive mixed-potential-type NO₂sensors based on yttria-stabilized zirconia (YSZ) electrolyte with high performance TPB (three-phase boundary) were fabricated. The sand blasting technology was utilized to construct high performance TPB on smooth YSZ-substrates. The SiC sand with different diameter (40, 60 and 80 mu m) was used to process YSZ substrate for improving the surface topography of YSZ. The results from SEM (scanning electron microscope) observation and roughness measurement showed that surface roughness of YSZ substrate increased with the increasing of SiC sand diameter. And a high performance three-phase boundary was constructed to enhance the sensitivity of the sensor. In comparison with other sensors, the sensor using the YSZ-substrate processed by 80 mu m SiC gave the largest signal to NO₂at 850 degrees C, whose response to 100 ppm NO₂was about 1.08, 1.21 and 1.5 times higher than those for the sensors based on YSZ-substrate blasted by 60 mu m SiC, 40 mu m SiC and the smooth YSZ substrate, respectively. It was also seen that the sensor showed a good stability and speedy response kinetics. The improvement of NO₂-sensing properties might be due to the enlargement of the area of three-phase boundary.