Abstract: Plasma treatment is a kind of ripe microelectronics technology. Applying R.F. glow discharging to process the surface of the Triethanolamine coating on the QCM (Quartz Crystal Microbalance) sensor, the QCM sensor’s performances are well ameliorated. Experiments indicate that the processed sensor has preferable sensitivity to aldehyde. The sensor has a series of virtues, such as good reappearance, short response time, stable performance, easier to regenerate and much longer lifetime. In this paper, we discuss preliminarily the response mechanism of the sensor, the causation of the ameliorated characteristics and the factors that affect its performance.