Electron cyclotron resonance (ECR) ion source is employed to erode the surface of sapphire (crystal orientation C) and the eroding effects and optical properties beams are researched at different low energy Ar + ion-beam incident angles. The experimental results indicate that, with ion beam energy 1200 eV, and beam current density 265 μA/cm2 , the increase of incident angle (5° ~40° ) obtains dot patterns on the sample surfaces; when the incident angle continues to increase up to 45°, orderly ripple structures appear on sample surfaces; the increase of incident angle (45°~70°) achieves column structures on sample surfaces in the direction of incident angle and orderly ripple structures in the direction perpendicular to incident angle; with the increase of incident angle, ripple wavelength on the sample surface firstly decreases slightly (45°~60°) and then gradually enlarges (60° ~70° ); when the incident angle is within 70° ~75° , dot patterns with larger aspect ratio emerge on sample surfaces. Eroding time extension is unable to change nano-struture topographies, but able to increase the vertical nano-structure dimensions and enhance the orderliness. In addition, enhancement of surface orderliness and height of nano-structures results in the increase of transmittance, which accounts for sample surface antireflections. The transformation of self-organized nano-structure patterns result from the interaction of spurting roughness and relaxation mechanism.