Abstract: Low-calcium high-strength clinker cement and fly ash were used as the main raw materials to prepare low-calcium high-strength clinker cement concrete specimens. Three mechanisms, namely, single chloride ion erosion, single carbonation erosion and chloride ions–carbonation erosion, were set up to conduct concrete erosion tests. The mass fractions of free chloride ions and total chloride ions were used as evaluation indexes to analyze the chloride ion erosion resistance of concrete specimens under the single chloride ion and chloride ions–carbonation. The carbonation depth and pH were used as evaluation indexes to analyze the carbonation resistance of concrete specimens under the single carbonation and chloride ions–carbonation. The pore structure and micro-morphological characteristics of concrete specimens were analyzed by nitrogen adsorption method (BET) and scanning electron microscopy (SEM). The results show that, compared to the single chloride ion erosion, the internal erosion depth of concrete specimens subjected to combined chloride ion and carbonation erosion is essentially the same, at from 20 to 25 mm. However, the contents of free chloride ions and total chloride ions increase, while the content of combined chloride ion decreases. The most probable pore diameter increases by 8.1 nm, indicating a coarsening of the pore structure. The morphology shows irregular cluster-like C—S—H gel structures and a large amount of CaCO₃. Additionally, there is an increase in the number of pores,along with connectivity, leading to a decline in resistance to chloride ion penetration.Compared to single carbonation erosion, the internal carbonation depth of the concrete specimens subjected to the combined chloride ion and carbonation effect is reduced. Both the fully carbonated and partially carbonated zones are reduced. The pore structure is refined, and the micro-morphology exhibits chloride ion crystals and Friedel’s salt, which fill the pores, leading to a denser structure. As a result, the anti-carbonation performance of the specimens is significantly improved.