<p>AlCoCrFeNi high-entropy alloy (HEA) was added into the copper matrix as a reinforcement phase to solve the problems of insufficient hardness, poor wear resistance, and unstable friction properties of copper-based friction materials under heavy load and elevated temperature. Copper-based friction materials were fabricated by powder metallurgy, and the effect of AlCoCrFeNi HEA content on their microstructure, mechanical, and tribological properties was studied. The results show that with the increase in the content of AlCoCrFeNi HEA, the density of the material remains basically unchanged (about 4.95 g/cm³), and the hardness first increases and then decreases. When the content of AlCoCrFeNi HEA is 2 wt.%, the hardness reaches the maximum (23 HB). At the braking speed of 350 km/h, the coefficient of friction increased progressively with the addition of AlCoCrFeNi HEA, while the wear loss first rose and then declined. When the content of AlCoCrFeNi HEA is 5 wt.%, the friction coefficient reaches the maximum (0.377), the wear loss is relatively low (122 mg), and the comprehensive performance is the best. With the increase in AlCoCrFeNi HEA content, spalling pits and cracks gradually decreased, and the wear mechanism changed from abrasive wear to fatigue wear.</p>