We investigate the vertical structure and element distribution of neutrino-dominated accretion flows around black holes in spherical coordinates with reasonable nuclear statistical equilibrium. According to our calculations, heavy nuclei tend to be produced in a thin region near the disk surface. In this thin region, we find that 56Ni is dominant in the flow with low accretion rate (e.g., 0.05M⊙s-1). The solutions indicate that 56Ni comes from the central engine, whose decay may drive the bumps in the light curve of core-collapse supernova.