The effect of SO2 in simulated furnace atmosphere on the corrosion behaviors of CoCrFeNiTi0.5 anti-alkali metal sulphate was investigated by means of XRD, SEM (EDS) and EMPA. The results show that the corrosion kinetic curve of the alloy in 0.75%SO2 follows the parabolic law and is similar to that in 0% SO2. The corrosion products are mainly composed of Ti，Cr，Fe oxides, minor compound oxides with spinals structure as well as (Fe,Ni)xSy. Adding 0.75%SO2 in simulated furnace atmosphere increases significantly the oxide films in thickness as well as the pore densities occurring in the corrosion affected zone, and accelerates the spalling of the oxide films off the surface of the alloy. It is concluded that the corrosion of CoCrFeNiTi0.5 high-entropy alloy in 0% SO2 is attributed to the formation of the protective oxide layers and to the basic fluxing of Cr2O3 in molten Na2SO4 induced by low melting point eutectic，however，the high temperature corrosion of CoCrFeNiTi0.5 in 0.75%SO2 is contributed to the oxidation of the alloy, the sulfate salinization of metallic oxide and the formation of ternary composed alkali metal sulfate as well as the dissolution of Fe in melted salt. Moreover, the sulfidition of Fe,Ni occurring in the corrosion affected zone is also contributed to the corrosion.