Oxide/metal/oxide multilayer-structured transparent electrodes are considered to be a promising alternative to indium tin oxide. In this research, ultra-thin metal-based transparent electrodes were deposited by a magnetron sputtering system to investigate the effect of high-vacuum annealing treatment on the microstructure, surface morphology, and optoelectronic properties of multilayer transparent electrodes. The experimental results showed that the high-vacuum annealing treatment affects the grain size and surface morphology of the films, which become denser, with lower losses to carrier scattering and improved optoelectronic performance of the transparent electrodes. After annealing at 200°C for 1 h under high vacuum, the ultra-thin metal-based transparent electrodes has better optical and electrical properties. The sheet resistance is 8.34 Ω/□, the average visible transmittance is nearly 96%, and the figure of merit is as high as 1 090.45/Ω. The results show that ultra-thin metal-based transparent electrodes have good thermal stability and excellent optoelectronic performance.