Thinning of silicon chip is necessary to save silicon material and to use it more efficiently in solar cell industry.However,the process of thinning silicon chip may cause defects and stress concentration on chip surface which resulting in chip failure.In this study,the finite element method was used to investigate the stress behavior at crack tip on the surface of silicon chip under four-point bending.Nanostructures were introduced on the tensile surface of silicon chip to alleviate the stress on silicon chip.The results show that the nanostructures on chip surface can effectively increase the mechanical strength of silicon chip.The maximum stresses at the crack tip on chip surface reduce 30% when compared with those on a polished chip surface.The maximum stress at the crack tip reduces for shorter crack and for thicker silicon chip.These results can provide a reference for thinning and mechanical strength enhancement of silicon chip using nanostructure.