Irradiation can induce the formation of a large number of defects in the matrix and oxide film of zirconium alloys, thereby facilitating the migration and diffusion of O^2- and corrosive media and accelerating the corrosion of zirconium alloys. To investigate the influence of irradiation on Zr-Sn-Nb alloys, Ar⁺ was implanted into the alloys at an irradiation in fluence of 5.1×10¹⁵ ions/cm². The original and irradiated samples were subjected to corrosion tests in an aqueous solution of 360 ℃/18.6 MPa/3.5 μL/L Li+1000 μL/L B (alkaline water) and in steam at 400 ℃/10.3 MPa (neutral water), separately. The microstructure and the effect of Ar⁺ irradiation on the corrosion resistance of Zr-Sn-Nb alloys in different corrosion environments were analyzed by XRD, SEM, and TEM. The results indicate that irradiation can lead to the amorphization of the second phase particles, among which the hcp-Zr(Fe,Nb)₂ second phase is more likely to form an amorphous state phase than the bcc-β-Nb second phase. Furthermore, the second phase undergoes amorphization at the same time with element diffusion, and during the oxidation process of the second phase, it experiences lattice mismatch with the oxide film, resulting in cracks extending from the top of the second phase to its sides. Within 300 d, the damage dose of Ar ion irradiation at 5 dpa has little effect on the corrosion resistance of Zr-Sn-Nb alloys in the aqueous solution of 3.5 μL/L Li+1000 μL/L B. In contrast, in steam at 400 ℃/10.3 MPa, the stress relaxation during the irradiation process results in a reduction in defects, which subsequently slows down the oxygen diffusion within the oxide film and decelerates the corrosion process. Therefore, irradiation has a certain improving effect on the corrosion resistance of zirconium alloys.