In active temperature?controlled dew point measurement based on a quartz crystal microbalance (QCM), the viscoelastic property of liquid water leads to a frequency dissipation which has an effect on the detection accuracy of dew point. Here, the QCM electrode was modified by hydrophobic treatment to improve the condensation form, minimize the dissipation attributed to the water viscosity, and achieve the measurement of resonance frequency offset caused by changes in liquid water quality. A hydrophobic layer with a static water contact angle of 133° ± 2° was prepared on the QCM electrode and characterized. The hydrophobic electrode and untreated electrode were applied in the dew point recognition experiments, and compared with the standard dew point obtained by a precision dew point meter. The experiments proved that the hydrophobic treatment of the electrode surface can effectively improve the dew point recognition accuracy of the QCM sensor. The optimal approach can provide basis for the design of dew point sensor structure with active temperature control.