Al_xCuFeNiCoCr high-entropy alloys were prepared by powder metallurgy method. The effect of Al content on the properties and microstructure of the alloys was studied, and the change in the grain properties during the preparation of the alloys was discussed. The results show that the alloy grains are refined during the milling process, and the grain size of the alloy increases with the increase of Al content. New grains are generated in the alloy during the sintering process, and an intermetallic compound containing Al is initially formed by absorbing a certain amount of heat. A phase with simple crystal structure is obtained after heating at 1200 °C for 2 h, which confirms the formation of high-entropy alloy. Based on the obtained energy spectrum, the alloy composition is uniform, and the alloying degree is high. However, with the increase in Al content, a small number of high-contrast areas with high Al content emerge. The alloys exhibit a good high-temperature oxidation resistance and electrochemical corrosion resistance. The oxidation resistance at high temperature increases with the increase of Al content. The self-corrosion voltage is -235 mV when x=1.0. With the increase in Al content, the hardness also increases. The best overall properties of the alloy are achieved when x=1.0.