The output of quartz crystal microbalance (QCM) sensors is in the form of frequency signals. Thesesensors offer advantages such as low cost, fast response, and high sensitivity. This study utilized porous α-Al2O3,a moisture-sensitive material, to enhance the humidity detection sensitivity of QCM sensors. Simulations were performedusing COMSOL, by applying the QCM sensing principle, to investigate the influence of various structuraldimensions on the sensor’s resonant frequency, quality factor, and admittance, while optimizing its geometric parameters.Subsequently, the sensitivity and dynamic characteristics of the sensor were examined over a specific humidityrange. The experimental findings demonstrate the remarkable humidity discrimination capability of the sensor,with a maximum frequency response of 13 kHz, sensitivity of 155 Hz/(%RH), and response and recoverytimes of 20 s and 8 s, respectively. These results demonstrate the reliability and accuracy of the QCM sensor, utilizingporous α-Al2O3 as the moisture-sensitive material, in humidity detection.