The sub-wavelength micro/nano structure surfaces have an excellent anti-reflective property. Based on application foundation of silicon-based solar cells response spectrum of 300～1 200 nm, reflection characteristics of two-dimension micro/nano structure surface were calculated influenced by the surface face forms,structure parameters with duty ratio,height and period,and incident angle of light waves,using the finite difference time domain method.Further analysis was done by effective medium theory.The results show that the reflectivity is large for the grating structure of uniform section,and the influence of structure parameters is small; anti-reflective performance of a taped gradient section structure is much better,and the reflectivity is observably reduced with duty ratio and height increased; and it also showed that the reflectivity is a little smaller at the incident angle range of ±40°.The simulation and analysis on reflective property of sub-wavelength micro/nano grating structure,provide the basis on the design and fabrication of anti-reflection surfaces.