The propagation process of crack in the nanocrystalline Ni is simulated via the quasicontinuum method. The results show that the stress near the crack tip could prompt the disassociation of grain boundaries, and the formation of stacking faults and deformation twins. Farther from the crack tip, fewer deformation twins can be found. There are more stacking faults than deformation twins in the grains, which approximately have the same distance to the crack tip. The effect on deformation twins from the variation of local stress and generalized planar fault energies is manifested by these results. The distribution of hydrostatic stress on atomic-level around the crack tip is also calculated. It is shown that nanovoids can be easily created in grain boundaries in front of the crack tip. There exists an intense tensile stress state in the grain boundary regions around these nanovoids. As a result of the stress accumulation, the crack propagates along the grain boundaries. Our simulated results qualitatively uncover the propagation process of crack in nanocrystalline Ni, which agrees well with the relevant experimental results.