In this paper, a high performance YSZ based mixed-potential type sensor based on three-dimensionalthree-phase boundary (TPB) and a new type composite oxide Co₃V₂O₈as sensing electrode (SE) wasfabricated for NO₂detection at 700℃. The Co₃V₂O₈material was synthesized through sol–gel method, and the YSZ particle was mixed uniformly with Co₃V₂O₈in different mass fraction (0 wt%, 10 wt%, 20 wt%,30 wt%, 40 wt% and 50 wt%) to form different three-dimensional TPB. The present study mainly focusedon the effect of the TPB on NO₂sensing performances of sensor. Results showed that the sensor using sensing electrode Co₃V₂O₈+ 40 wt% YSZ displayed the largest sensitivity in an NO₂concentration range of10–400 ppm at 700℃, which the slope was 85 mV/decade. The response for the sensor to 100 ppm NO₂was approximately 130 mV. Furthermore, the present sensor also displayed relatively good linearity, repeatability, stability, and cross-sensitivities. Such an enhancing effect on the sensing characteristics of the sensor may be ascribed to the enlargement of three-phase boundary through constructing the three-dimensional TPB.