Abstract : The piezoelectric quartz sensor(PQS) was prepared by coating metal phthalocyanines(PcM) sensitive to nitrogen oxide(NOx) on the surface of Au electrode of quartz crystal resonator by electrochemical activation and silane coupling agent. The response sensitivities and detec2 tion limits of a variety of materials to NOx ,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 NOx ,that the appropriate flow velocity of carrier gas was 40 mLPmin and temperature range was 10~40 ℃,that the responses of sensor are fairly linear when the mass concentration is from 9155 ×10 - 4 to 1191 mgPm3 ,and that it has a good reliability and accuracy in the determination of NOx in the atmosphere. It could be used about 300 times. Key words : piezoelectric quartz sensor(PQS) ; nitrogen oxide (NOx) ; response sensitivity ; detection limit