The development of high-performance nitrogen dioxide gas sensors is indispensable and critical for environmental monitoring and medical fields. Different nanostructural ZnO were efficiently synthesized via a microwave-assisted gas-liquid interface method and the gas sensing performance of ZnO-based gas sensors with different morphologies was comparatively investigated. The results show that the ZnO-3 sensor (microwave reaction temperature is 180 ℃) has the best sensing performance to NO2 at lower operating temperature (120 ℃). It exhibits a high response (Rg/Ra = 397), short response/recovery time (21 s/30 s), and good selectivity to 100 ppm NO2. Moreover, the ZnO-3 sensor exhibits remarkably high response (185 to 100 ppm NO2) even at 25 ℃. In addition, the ZnO sensor can maintain good stability and repeatability in long-term cycling tests to 5 ppm NO2. Evidently, this research offers a reference value for the efficient synthesis of ZnO nanomaterials and real-time detection of nitrogen dioxide emissions.