The durability issue of multi-age masonry structures subjected to acid rain has become increasingly prominent， but a complete time-varying model of structural durability has not been formed at home and abroad. To study the relationship between the evolution of material properties and masonry properties， accelerated corrosion tests were carried out on mortar with different mix ratios， bricks， and masonry， and a compressive strength model of masonry components considering the number of acid rain erosion cycles was established. Based on the sample data of masonry in natural environment， the mathematical relationship be? tween the degradation degree of mechanical properties of in-service masonry structures and their service life under the action of acid rain erosion was established. The typical structure method was used to analyze the seismic fragility of a two-story constrained ma? sonry structure， and the influence of different parameters on the fragility curve and failure probability of constrained masonry struc? tures under acid rain erosion was discussed. The results show that the probability of severe damage and collapse of restrained ma? sonry structures under the action of acid rain erosion increases gradually with the increase of service life under the condition that oth? er factors remain unchanged and the intensity of local vibration is higher.