AlCoCrFeNiSix (x=0, 0.2, 0.5, 0.8, 1.0) high entropy alloys were prepared by vacuum arc melting. The effects of Si addition and its content on the hot corrosion behavior of AlCoCrFeNi alloys at 950℃ in mixed salt of 75% Na2SO4 + 25% NaCl (mass fraction) were investigated. The results showed that the surface phase composition of the alloys changed from BCC to FCC due to selective oxidation of Al after 100h hot corrosion. A single Al2O3 scale could be formed preferentially on the surface of the alloy by adding proper amount of Si, and the hot corrosion resistance of the alloy can be improved significantly. However, the mixed oxides scales mainly composed of Al2O3 and Cr-Fe-Co-Si enriched spinel oxides formed on the surfaces of the alloys with the increase of Si content. Under the synergistic action of the growth stress of mixed oxides scale and the multi-element corrosion medium (oxidization-vulcanization-chlorination), the oxide scales were loose and easy to fall off, and serious internal oxidation and vulcanization were observed in the alloys.