The challenging wind conditions surrounding power transmission lines exacerbate the wear and corrosion of transmission line fittings. Thermal diffusion galvanizing technology, a novel method for obtaining galvanizing layers, significantly enhances the wear and corrosion resistance of metal components, thereby extending their service life. Holding temperature plays a critical role in determining the performance of the thermally diffused zinc coating. In this study, we prepared thermally diffused zinc coatings containing rare earth oxides on 35CrMo steel at various holding temperatures and evaluated their morphology, wear resistance, and corrosion resistance. The findings indicate that increasing the holding temperature enhances the diffusion of zinc and iron, yielding thicker coatings with a maximum thickness of 60 μm at a holding temperature of 450 °C. Notably, the zinc coating produced at a holding temperature of 410 °C exhibits optimal wear resistance at room temperature, and the wear failure mechanisms were predominantly abrasive wear and oxidative wear with slight adhesive wear. In addition, the zinc coating produced at a holding temperature of 430 °C exhibits optimal corrosion resistance at room temperature.