The nano silicon tips were fabricated by KOH solution with the anisotropic wet etching technique based on self sharpening effect were investigated.In order to improve the aspect ratio of the silicon tip,the effects of the solution concentration and the shape of etch mask on the shapes of silicon tips were studied by the tip self sharpening model.Simultaneously, the self sharpening conditions of the tip on (100) silicon wafers were obtained.The results showed that the nano silicon tips were formed by the anisotropic etching in 15 mol/L KOH etchant at 60 ℃ with the pentagon etch masks, The self sharpening nano silicon tips with {113} etch planes had a radius of curvature of <10 nm.