The work aims to obtain the alloy film with good resistance stability by changing the thickness of the film, increasing the protective film and adopting the Cradient thermo treatment process. Ion beam sputtering process was used to deposit 160 nm and 300 nm thick alloy thin films and 200 nm thick SiO2 protective films. Cradient thermo treatment process was adopted to carry out vacuum heat treatment to thin films. The Agilent digital multimeter was used to test the resistance value before and after heat treatment and the difference value was adopted to calculate the resistance change to study the film resistance stability. Compared with the resistance change in 160 nm alloy thin film, the resistance change in 300 nm thick films before and after heat treatment respectively decreased to 2 ? from 25 ?. Compared with the resistance change in alloy thin films without protective film before and after the heat treatment, the resistance change in the film with protective film dropped to 25 ? from 76 ?. Compared with the direct heating process of thin film, the resistance change in the film processed by Cradient temperature rising method lowered to 25 ? from 46 ?. Moreover, the resistance stability of film improved. The increase of alloy film thickness can reduce the boundary and impurity effects of film and improve the resistance stability of thin film. Increasing the protective film can prevent the water and vapor in the external environment from affecting the film. The Cradient temperature rising method is beneficial for the film to fully release the residual stress and improve the resistance stability of thin film.