The fretting degradation of coating materials is complicated when the Joule heating effect of the load current is non-negligible. In this work, the fretting degradation behavior of tin-coated copper alloy contacts was examined across the current range from 5 A to 30 A and the fretting amplitude range from 200 μm to 400 μm. The uniform degradation process and associated mechanisms, including the wear-dominated stage, softening-dominated stage, and oxidation-dominated stage were recognized and interpreted explicitly. An innovative fusion model for the degradation of electrical contact performance, data-driven and based on physics mechanism, was proposed. The contact voltage was selected as the characterization variable and pre-processed by the threshold-crossing filter method and the Levenberg–Marquardt algorithm. The optimal degradation model, considering the coupled effects of current and fretting amplitude, was presented with the use of the support vector regression method. Finally, the prediction accuracy of the model was validated by experiment results.