Abstract: Hydrogen energy is one of the most promising clean energy sources to replace fossil energy, which has the advantages of easy production, high efficiency and clean environmental protection. However, when the hydrogen concentration reaches 4%~75.6%, it is very easy to explode, so in the process of hydrogen production, storage, transportation, distribution and application, hydrogen concentration monitoring is extremely important. In this paper, a PdNi alloy film with a thickness of 90 nm was prepared by magnetron sputtering technology and MEMS process. To solve the zero drift problem of the hydrogen sensor of the PdNi alloy film, air and argon were used for annealing treatment, and the annealing temperature and time were set at 250℃ and 2 h. Subsequently, the hydrogen sensitive response characteristics of PdNi alloy thin film hydrogen sensors under different annealing atmospheres were tested. The results show that after air annealing, the PdNi film is seriously oxidized and cannot respond well to H₂. After Ar annealing, the alloying degree of PdNi thin film is enhanced, the film defects are reduced, the response value and sensitivity of the PdNi alloy thin film sensor are reduced, and the response time is prolonged, but the material structure will be more stable, and the zero drift of the sensor can be suppressed, which is about 50% optimized compared with the unannealed sample, and the sensor response is more stable.