Abstract: To investigate the tribological properties of AlCoCrFeNiCu high-entropy alloy in hydrogen peroxide with strong oxidizability, a series of pin-on-disk tribo-tests were carried out using AlCoCrFeNiCu as pin and three types of engineering ceramics (ZrO₂, SiC and Si₃N₄) as disk in a 90% hydrogen peroxide. The characterization techniques, including white light confocal microscope (CM), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS), were employed to analyze the worn surfaces, and the wear mechanism of AlCoCrFeNiCu/ceramic tribo-pairs was discussed. The results showed that when sliding against SiC and Si₃N₄ ceramics, the AlCoCrFeNiCu pins had mild wear and low friction coefficient. The wear mechanism of AlCoCrFeNiCu/ZrO₂ tribo-pair was a combination of adhesive wear, abrasive wear and oxidative wear. Both AlCoCrFeNiCu/SiC and AlCoCrFeNiCu/Si₃N₄ tribo-pair exhibited polishing oxide wear and three-body abrasive wear. The effect of boundary lubrication was found for AlCoCrFeNiCu/Si₃N₄ tribo-pair.