Metal oxide film, formed on the surface of cladding tube deriving from radiolysis of cooling water under neutron irradiation, has outstanding irradiation stability and abrasion resistance. This study tends to investigate the effect of ion irradiation on wear behaviors of pre-oxidized Zr-4 alloy. Microstrcture and mechanical properties of pre-oxidized Zr-4 alloy before and after irradiation were examined comparatively and the internal correlations be-tween microstrcture, mechanical properties and tribological behaviors were further investigated. The results indicated that the irradiation could result in phase transition and reduction reaction of ZrO2 layer. Raman spectra evidenced that the irradiation of pre-oxidized Zr-4 alloy with 3 MeV Fe11+ ions could result in a transformation from monoclinic ZrO2 to tetragonal ZrO2. XPS verified that the Fe11+ irradiation reduced ZrO2 to Zr2O3, which could be assigned to the bombardment-induced Gibbs segregation (BIS) or lattice relaxation. Friction tests results showed that the formation of ZrO2 film could promote the abrasion-resistance properties of Zr-4 alloy before and after irradiation owing to the increase of hardness and the change in intrinsic wear mechanism.