Abstract: In order to study the fracture characteristics of cement-based composite materials under the solid waste steel slag and erosion of sulfate solution, the polyvinyl alcohol fiber reinforced cement-based composite materials (PVA/ECC) were prepared by adding different mass fractions of steel slag powder. Three-point bending performance test was conducted on prefabricated initial crack beam specimens after sulfate erosion. Combined with the apparent morphology and microstructure characteristics of steel slag powder PVA/ECC in Na₂SO₄ solution (mass fraction of 5wt%), the effect of sulfate corrosion on the fracture performance of steel slag powder PVA/ECC was investigated. The results show that when the content of steel slag powder without sulfate attack is 20wt%, the cracking load and instability load of the specimen are the best, with an increase of about 61% and 110% compared to the specimens without steel slag powder, respectively. The fracture toughness of PVA/ECC first increases and then decreases with erosion time, reaching its peak after 60 days of erosion. After 120 days, the S80 group shows the most obvious degradation, with the initiation toughness K\mathrm^ini and instability toughness K^\mathrmu\mathrmn decreasing by about 23% and 13%, respectively. The addition of an appropriate amount of steel slag powder can effectively alleviate the erosion damage of PVA fiber reinforced cement-based composite materials. When the amount of steel slag powder does not exceed 60wt%, there is no significant deterioration of the material within the age range of the experimental study. On this basis, the durability life of the specimens was predicted using a Weibull distribution model, PVA/ECC with a 20wt% steel slag powder content having the longest service life, reaching around 444 cycles.