The mixed-potential NOx sensor based on yttria-stabilized zirconia (YSZ) and oxide electrode is considered as a potential device used for the on-board diagnostics. Over the past decades，many researchers have paid their attentions on such YSZ based potentiometric NOx sensors and gotten a lot of achievement in developing new type electrode materials. Recently，in order to enhance the sensing performance of the mixed potential type NOx sensor，we have been focusing on modifying the triple-phase-boundary (TPB) by various techniques，including chemical corroding，the double-tape casting，the pore-forming and laser fabrication method. We also designed and prepared the microstructure of the oxide electrodes by controlling the sintering process for increasing the sensitivity of the NOx sensor. This paper reviews our works with regard to the above-mentioned two aspects.