Objective <p>This paper innovatively considered the influence of the non-uniform temperature distribution within the drying oven and the periodic tension disturbances caused by changes in the diameter of the material rolls, which significantly affect the film during the production process. The paper investigated the primary parametric resonance of viscoelastic moving films with time-variant tension under thermal loading.</p> Methods <p>The nonlinear vibration equations for viscoelastic moving films with time-variant tension under thermal loading are derived by employing the Kelvin viscoelastic constitutive relationship and the Hamilton principle. The instability response of the film system is solved using the multiscale method and the Routh-Hurwitz criterion. The amplitude-frequency characteristic curve of the system is obtained by using MATLAB for numerical analysis.</p> Results <p>The findings indicate that the rise of tension variation coefficient and initial tension widens the primary parameter resonance region. The increase in drying temperature shifts the primary resonance interval towards higher values. The rise of the viscoelastic coefficient does not affect the primary resonance region of the system.</p> Conclusion <p>This paper provides a new theoretical basis for the motion stability of viscoelastic films in practical engineering applications.</p>