Wet FGD is the main technology used for the SO2 emissions control in coal-fired power plants in China, but there is still SO3 in flue gas after desulfurization, as well as a little SO2. Without gas-gas heater （GGH）, the flue gas humidity in chimney is high, so it belongs to wet chimney, whose corrosion grad is strong, and preferred structure scheme is multi-flue chimney. Through the comparison of outer tube forms of chimneys: cylinder, square tube and tower, it shows that the reinforced concrete cylinder is the most suitable to the outer tube of chimney. After comparing four wet anti-corrosion schemes of inner tube of wet chimney including titanium steel composite plate, FRP, nickel-base alloy and Pennguard anti-corrosion glass block, the FRP inner tube is recommended as an ideal anti-corrosion scheme for wet chimney in 1 000 MW coal-fired units.