Abstract: This dissertation aimed at the research direction of the etching result and optical property of sapphire. The microwave cyclotron resonance ion source was selected as the research instrument. The incident angle and incident energy of Ar+ ion beam were the parametric variables of the research. The research indicates that different variables can lead to different results. When the incident energy is limited to the levels of 800 eV, 1 000 eV and 1 200 eV, the transmittance achieves a big improvement from 50% to around 75%. The biggest and smallest increase of transmittance appear with the incident energy of 1000ev and 1200ev respectively. Besides, under the circumstances of same incident energy and different incident angles, the roughness of etched sapphire shows the tendency of firstly increasing and then decreasing. However, under the opposite circumstances the roughness does not show significant regularity. In addition, the surface morphology test after etching also receives different results. When the incident angle is constant and the incident energy is 1 000 eV, the point-like nanostructure turns up. Increasing the energy to 1 200 eV, the columnar nanostructure turns up. After variables are swapped, the incident energy is constant,the regular point-like nanostructure or strip-like nanostructure show up with the incident angles of 10, 50 and 80. When the incident angle is set in 30, the surface of sapphire is smooth.