In order to clarify the durability of iron tailings concrete under complex environment, the damage characteristics of iron tailings concrete under the coupling action of freeze-thaw cycle and sulfate erosion were studied. A freeze-thaw cycle test was carried out on the prepared iron tailings aggregate concrete in 5% (mass fraction, the same below) Na₂SO₄ solution to analyze the changes of mass loss, relative dynamic elastic modulus and compressive strength loss. Combined with damage mechanics, the degradation process of iron tailings concrete under coupling action was studied with ultrasonic wave velocity as damage variable, and a compacted model of iron tailings concrete was established by analyzing the relationship between ultrasonic wave velocity, elastic modulus and porosity. The results indicate that the mass of iron tailings concrete shows a phased increase after 20 cycles, followed by a decreasing trend. The relative dynamic elastic modulus and compressive strength decrease at first fast, then slow and then fast. Compressive strength loss is positively correlated with concrete damage degree, and ultrasonic wave velocity, elastic modulus and porosity are inversely proportional. Under the coupling action of freeze-thaw cycle and sulfate erosion, the deterioration rate of iron tailings concrete is the fastest. This study can provide reference value for the application of iron tailings concrete in complex cold environment.