An ultrafast-response yttria stabilized zirconia (YSZ)-based mixed potential type gas sensor utilizing molybdate CoMoO4 sensing electrode was developed to realize the effective detection of triethylamine (TEA) at 600℃. The gas sensing characteristic of the fabricated sensor was optimized by changing the calcination temperature of CoMoO₄sensing material and results indicated that the device attached with CoMoO4-SE sintered at 1000℃ exhibited the highest response value (-102 mV) to 100 ppm TEA and low detection limit of 100 ppb at 600 ℃. Interestingly, the response and recovery times of the present sensor to 100 ppm TEA were 1 s and 10 s, which signified the ultra-fast response rate. The response value of fabricated sensor displayed the piecewise linear function to logarithm of TEA concentrations and the sensitivities were -14 mV/decade (0.1-5 ppm) and -53 mV/decade (5-200 ppm), respectively. More importantly, the present sensor also exhibited good repeatability, selectivity, slight effect of humidity and long-term stability of 20 days, indicating a great candidate for use in detection of TEA. Furthermore, the device based on mixed potential mechanism was proposed and further verified using polarization curve.