Abstract: In order to investigate the affect of Zr-ion bombardment on the corrosion resistance of zir-caloy-4, specimens were bombarded by zirconium ions with a fluence range from 1×10¹⁵ to 2×10¹⁷ ions/cm², using a MEVVA source at an extract voltage of 50 kV. The valence of the surface layer was analyzed by X-ray photoemission spectroscopy （XPS）; the thickness of the oxide film was measured by auger electron spectroscopy （AES）. Three-sweep potentiodynamic polarization measurement was used to value the corrosion resistance of bombarded zirconium in a 1N H₂SO₄ solution. Slow positron annihilation spectroscopy （PAS） measurement was employed to obtain to the distribution of the implantation induced defects. A significant improvement of corrosion resistance was achieved compared with as-received zircaloy-4 except for 1×1015 Ions/cm² fluence, and the sample with 5×10¹⁶ ions/cm² fluence is most anti-corrosive in all the samples. The natural corrosion potentials of bombarded samples decline with raising the bombarded fluences. It was found that there was some relationship between the corrosion behavior of Zr-ion bombarded zircaloy-4 and the slow positron annihilation spectroscopy （PAS）.