A quantitative experimental study with digital image correlation (DIC) algorithm on shear banding deformation behaviors of high purity, fully dense nanocrystalline Ni sheet subjected to quasi-static uniaxial tensile load was carried out. Based on that, onset and evolution of shear bands in nanocrystalline Ni were analyzed, and some critical points, such as shear band nucleation, broadening process and failure point were recognized quantitatively. Finally, the physical characteristics of shear bands, such as inclination and width, were discussed. Results show that the nanocrystalline Ni exhibits shear localization in the form of shear band, which is the main reason of the early failure during plastic deformation