Abstract: High-entropy alloys, leveraging the four core effects as high entropy, lattice distortion, sluggish diffusion, and cocktail effect, possess the advantages such as high activity, excellent selectivity, corrosion and heat resistance, and structural stability, effectively compensating for the scarcity and high cost of the traditional noble metal catalysts. The high-entropy alloy catalysts have been widely applied in electrocatalysis, photocatalysis, and thermocatalysis, which exhibit the outstanding performance in reactions such as hydrogen evolution, oxygen evolution, CO₂ conversion, and organic pollutant degradation. The mainstream preparation techniques of high-entropy alloy catalysts were systematically reviewed in this paper, including mechanical alloying, carbothermal shock, and rapid moving-bed pyrolysis, and the advantages, disadvantages, and applicable of these preparation techniques were analyzed. By leveraging the computational materials science and advanced characterization techniques, the bottlenecks of high-entropy alloy catalysts in terms of alloy design, catalytic mechanism, stability, cost, and process could be addressed, which is expected to enable the large-scale industrial applications in hydrogen energy, fuel cells, and resource utilization of greenhouse gases, thereby contributing to the green development of the energy and environmental industries.