In this study, amperometric NO2 sensors based on Na+ superionic conductor electrolyte and sensing electrodes with different WO3 nanostructures (WO3 nanoparticles, WO3 nanosheets, and mesoporous WO3) have been fabricated and compared. Sensing properties, such as optimum test temperature, sensitivity, repeatability, and selectivity have been determined and compared. Compared with the literatures, the sensors, prepared using three different WO3 nanostructures, all showed improved sensing properties to 100-1000ppb NO2 at low work temperatures of 100-150 degrees C. Among above sensors, the sensor equipped with mesoporous WO3 sensing electrode exhibited the best amperometric sensitivity characteristics and the minimum test temperature. The relationship between the sensing properties and the mesoporous structure has also been discussed. What's more, the sensor can test ppb-level NO2 in low temperature, which makes it possible to monitor low concentrations of NO2 in the air.