Oxygen and water vapor significantly affect the hydrogen sensitivity of PdNi thin films. To achieve hydrogen concentration monitoring in environments containing oxygen and high humidity—such as electrolytic water hydrogen production stations, nuclear power plant storage, and deep-sea energy exploration—PdNi thin film hydrogen sensors were fabricated using magnetron sputtering, photolithography, and plasma etching. By controlling the Ni content and thickness of the PdNi films, this study investigated their influence on sensor stability under oxygen and humid conditions. Characterization techniques including XRD (X-ray Diffraction), SEM (Scanning Electron Microscope), and XPS (X-ray Photoelectron Spectroscopy) were employed to analyze the crystallinity, elemental composition, and valence states of the films. Experimental results indicate that higher Ni content leads to greater susceptibility of the PdNi film's hydrogen response to interference from water vapor and oxygen. Conversely, increased film thickness mitigates this interference effect, albeit at the cost of reduced intrinsic response sensitivity. Notably, a PdNi film sensor with a thickness of 24 nm and Ni content of 8.02% demonstrated the ability for its response curve to recover to its pre-exposure state after experiencing water vapor, despite being affected by both water vapor and oxygen.