Abstract: The piezoelectric quartz sensor(PQS) was prepared by coating metal phthalocyanines(PcM) sensitive to nitrogen oxide(NO_x) on the surface of Au electrode of quartz crystal resonator by electrochemical activation and silane coupling agent.The response sensitivities and detection limits of a variety of materials to NO_x,and effects of the flow velocity of carrier gas,temperature and recovery characteristics of sensors were investigated.The results indicated that lead phthalocyanine was the most sensitive to NO_x,that the appropriate flow velocity of carrier gas was 40 mL/min and temperature range was 10~40 ℃,that the responses of sensor are fairly linear when the mass concentration is from 9 55×10_-4 to 1 91 mg/m₃,and that it has a good reliability and accuracy in the determination of NO_x in the atmosphere.It could be used about 300 times.