Abstract: The hot corrosion behavior of TP347HFG,316L and C-HRA-5 austenitic heat resistant steels in sulfate environment at 650,750,850 ℃ was studied. The hot corrosion mechanisms of three kinds of austenitic heat resistant steels in sulfate environment were investigated by corrosion kinetics curves and corrosion product composition and morphology analysis. The results show that the three kinds of austenitic heat resistant steels displayed an increase in mass after corrosion, with a declined order of 316L, TP347HFG, C-HRA-5. When the temperature was low, the protective oxide layer on the substrate surface underwent corrosion and dissolution under the mechanism of “synergistic melting”. When the temperature was high, the oxide layer underwent severe corrosion under the dual mechanism of “synergistic melting” and “alkaline melting”. The austenitic steels had good corrosion resistance because of high content of Cr and Ni, and the addition of Cu element improved the high temperature corrosion resistance of austenitic steel to a certain extent.