Abstract: In order to make alkali-activated fly ash concrete more widely used in engineering, the influence of alkaline activator on the durability of fly ash concrete was studied, and the durability of alkali-activated fly ash concrete in different saturation( 30%,60%,100%) and different sulfate solution concentration( 0,5%,10%) were studied.The damage of specimens was evaluated from the aspects of appearance damage, mass loss, compressive strength loss and dynamic elastic modulus loss of alkali-activated fly ash concrete, and the erosion damage mechanism of specimens under sulfate erosion and freeze-thaw cycle coupling was analyzed by electron microscopy scanning technology.The results showed that the frost resistance of the specimens in 100% saturation was the worst in the 10% sodium sulfate solution.The compressive strength loss and dynamic elastic modulus loss of alkali-activated fly ash concrete had two stages of steady decline and accelerated decline.The deterioration degree of unsaturated specimens decreased with the decrease of saturation, so the durability under unsaturated conditions was better.Through theoretical analysis and laboratory test, a damage model of alkali-activated fly ash concrete with different saturations under sulfate erosion and freeze-thaw cycle coupling was established.