A series of high-performance quartz crystal microbalance humidity sensors were fabricated by using acidized-multiwalled carbon nanotubes (MWCNTs) as sensing film. The detection process is carried out in the static humidity generator at room temperature. The material characteristics of the thin films were analyzed by Raman spectra, X-ray photoelectron spectroscopy, FT-IR spectroscopy, and transmission electron microscopy. The experimental results manifested that acidized-MWCNTs exerted high-excellent dynamic response sensitivity (frequency shift reached -21037 Hz at 95%RH), fast response-recovery time (49s/6s), logarithmic linear relationship, small humidity Hysteresis, and outstanding reproducibility and reversibility. Furthermore, the adsorption dynamics of water vapor molecules mechanism was also analyzed.