Morse potentials were employed to carry out three-dimensional molecular dynamics simulations. A computer experiment was performed at the temperature corresponding to 300 K and 1000 K. MD simulation was used to investigate the effect of cross-sectional area of Ni nanofilm on the nature of deformation and fracture. The engineering stress–time diagrams obtained by the MD simulations of the tensile specimens of these Ni nanofilms showed a rapid increase in stress up to a maximum followed by a gradual drop to zero when the specimen was failed by ductile fracture. The feature of deformation energy can be divided into four regions: quasi-elastic, plastic, flow, and failure. The results shows that breaking position depends on the nanofilm cross-sectional area.