The influence laws of different fly ash dosage and curing regimes on the macroscopic mechanical properties, ion erosion resistance and microscopic pore structure of concrete are explored. The internal correlations among fly ash dosage, steam curing regime, macro-microscopic properties and ion erosion resistance of concrete are revealed. Through mechanical property tests, potentiometric titration and pore structure tests, the macroscopic and microscopic properties of concrete with different fly ash dosages and curing regimes are systematically investigated. The results show that the compressive strength of concrete decreases with the increase of fly ash dosage. At the same fly ash dosage, the 1 day compressive strength of steam-cured concrete is 36.2% higher than that of standard-cured concrete. With the increase of fly ash dosage, the chloride ion binding capacity of steam-cured concrete is gradually enhanced and the sulfate ion reaction coefficient decreases slightly. When the fly ash dosage reaches 45%, the steam-cured concrete exhibits the optimal macroscopic and microscopic properties. The pore size peak of steam-cured specimens is higher than that of standard-cured specimens and the steam curing increases the proportion of transition pores and capillary pores in the total porosity, while reducing the proportion of gel pores.