In general, the final product of atrazine (ATR) degradation by reactive oxygen species is cyanuric acid bearing a stable s-triazine ring, which is not further oxidized under mild conditions. In this study, we demonstrate that the presence of Ni(II) can increase the aerobic ATR degradation rate of core-shell Fe@Fe2O3 nanowires (CSFN) by 6 times and also achieve the cleavage of recalcitrant s-triazine ring. The cleavage of s-triazine ring in this novel system was confirmed by the measurements of formic acid and nitrite acid. On the basis of experimental results, a feasible mechanism was proposed to account for the promoted aerobic ATR degradation and the facile striazine ring cleavage as follows. First, Ni(II) adsorbed on the surface of CSFN was reduced to nickel metal, which favored the generation of active hydrogen (center dot H). The in-situ generated center dot H then reduced ATR to 4-ethylamino-6-isopropylamino-1,3,5-triazine intermediate of easy ring opening property, rather than the recalcitrant cyanuric acid. Finally, this ATR degradation pathway change promoted the aerobic ATR degradation and benefited the s-triazine ring cleavage. This study clarifies the importance of degradation pathway on the ring-opening of organic pollutants, and also provides a mild method to remove s-triazine herbicides with molecular oxygen and zero-valent iron.