<p>Refractory high-entropy alloys (RHEAs) have excellent mechanical properties at high temperatures and show significant application potential in extreme environments such as aerospace and nuclear reactors. The inherent high-entropy effect, sluggish diffusion effect, lattice distortion effect, and “cocktail” effect of RHEAs endow them with high strength, excellent oxidation resistance, corrosion resistance, and wear resistance, demonstrating stronger competitive advantages compared to traditional alloys. However, the alloy composition and preparation methods significantly affect the high-temperature mechanical properties and oxidation resistance of refractory high-entropy alloys. This work systematically reviews the effects of different elements and preparation processes on the mechanical properties and oxidation resistance, investigating the mechanisms of mechanical property enhancement, oxidation behavior, and failure mechanisms of RHEAs. Furthermore, this study compares the microstructure and mechanical properties of the same RHEAs prepared using different techniques, analyzing the influence of the processing method on their structure and performance.</p>