The corrosion within direct aircooled condenser duct in powerplant is particularly serious， due to the bad gas-liquid environment and the ease of corrosion of 20^#carbon steel (20^#) .In this paper， 3004 aluminum alloy(3004) and 304 stainless steel(304) is adaptive to instead of 20^#.Study on corrosion of three materials was carried in a self-made device simu-lating actual operation environment of ACC， including hanging piece simulating corrosion，polarization curve and Electrochemical impedance spectroscopy(E IS) .It was to analyze the influence of the fluid temperature， dissolved oxygen and pHon the corrosion of three mate-rial and compare the corrosion resistance of three materials.The results show that the cor-rosi on rate of 20#is more than 10~1000 times that of 3004 and 304.The performance of resistance scale on the 3004is better than that on the 20^#and 304， and 304is better than 20#.EIS of 304 has the Warburg impedance.Electrode reactions are mixed control， the flu-id temperature and dissolved oxygen have much influence on the 20^#over 3004 and 304.3004hasa better application prospect in techno-economical analysis.