Amorphous alloys are meta-stable materials with long-range disordered atomic structure, which have excellent catalytic degradation performance and are also susceptible to crystallization, but the mechanism of the effect of crystallization on their catalytic properties has not been clarified. Therefore, the effect of the annealing crystallization process on the microstructure of Fe-Si-B-Cu-Nb industrial amorphous ribbons and their catalytic degradation properties for acid orange 7 are investigated in this work. It is found that the catalytic degradation performance of the ribbons decreases dramatically after having been annealed at 460–580 ℃ , and its reaction rate constant is less than 0.01 min ^–1. The main reason is the formation of α-Fe precipitation phase in the ribbons after having been annealed at high temperatures and the destruction of the substable amorphous structure. These reduce the rate of hydroxyl radical formation. In contrast, the catalytic degradation performance of the 650–700 ℃ annealed ribbons increases significantly, which increases to 3.77 times the degradation rate of the as-cast ribbons. The decolorization rate of acid orange 7 by the annealed ribbons reaches 99.22% within 15 min, which is 1.12 times that of the as-cast ribbons. The improvement of the catalytic degradation performance is attributed to the primary cell effect between the crystalline phase and the metal compounds and the substitution reaction between the Cu-enriched clusters and zero-valent iron. In this study, the influence mechanism of annealing crystallization on the performance of Fe-Si-B-Cu-Nb industrial amorphous ribbons for degrading azo dyes is revealed, which provides theoretical and experimental support for using aged iron-based amorphous ribbons to purify printing and dyeing waste-water and achieve “purification of waste-water by using alloy waste”.