The fully dense electrodeposited nanocrystalline Ni sample with dimensions at tens of millimeters was characterized under quasi-static uniaxial tensile load. During testing, the sample exhibited high strength simultaneously with a decrease in tensile strain. To inspect this early failure of the nanocrystalline Ni sample in this article, the strain fields of the sample were quantified with digital image correlation algorithm, and strain localization phenomenon in the form of shear band was captured successfully. Meanwhile, the failure mode and fracture surface of the Ni sample were examined in detail. The results suggest that the shear banding is a main deformation mode in nanocrystalline Ni sample, and it is an important factor to induce the early failure of the sample during plastic deformation.