Abstract: To promote the effective use of Recycled Aggregate Concrete (RAC) in cold northern regions,we conducted three sets of RAC freeze-thaw cycling tests.The tests had substitution rates of 0,50%and 100% based on the low humidity curing strategy.The study analysed the macro and microscopic damage laws of RAC under the action of freeze-thaw cycle by testing its mass,dynamic elastic modulus,compressive strength,porosity,and pore size distribution.The study established the macro comprehensive durability index Q and pore composite parameter η based on the entropy weight theory and fractal dimension idea to comprehensively reflect the durability of RAC.The results showed that:The RAC produced varying degrees of macro and microscopic damages due to the increase in the number of freeze-thaw cycles and substitution rate.The increase in substitution rate also resulted in different degrees of damage.The macroscopic comprehensive durability index Q and the pore composite parameter η are better indicators of damage at each scale.A strong correlation between the two was established by determining the degree of damage.Using grey correlation analysis,it was found that macropores and microcracks are the primary factors that affect the macro-integrated damage of RAC.