In order to investigate the optical properties of silicon nanocone arrays with different sizes and shapes, the nanocone arrays are fabricated on silicon substrate by submicron dry etching process masked by self-assembled nano-particles. The morphology and optical properties of the nano-cone arrays are characterized. The results show that the nanocone arrays with excellent optical antireflection performance can be obtained when the plasma flow ratio of SF₆ and C₄F₈ is 12 sccm，27 sccm, the power is 750 W and the bias voltage is 25 V. By adjusting the etching time, silicon nanocone structures with similar morpho-logy and different sizes can be obtained. The reflectivity of 200 nm and 400 nm periodic silicon nanocone arrays is 2%~3%, while that of 800 nm periodic silicon nanocone arrays is close to and 10% higher than the reflectivity of silicon substrate, which indicates that the anti-reflectivity of sub-wavelength structure is more remarkable. The result reveals experimentally the dimensional and morphological effect of silicon nanocone array structures on the antireflective properties, which may shed some important insights on further investigation or application in optical devices.