The spontaneous dewetting transition (SDT) of nanoscale droplets on the nanopillared surface is studied by molecular dynamics simulations. Three typical SDT modes, i.e. condensing, merging and coalescing with flying droplets are observed, and the underlying physical mechanism is clearly revealed by the potential energy analysis of droplets. We find that there exists a dimensionless parameter of the relative critical volume of droplet Ccri which completely controls the SDT of nanodroplets. Furthermore, the Ccri remains constant for geometrically similar surfaces, which indicates an intrinsic similarity of nanoscale SDT. The effect of pillar height, diameter and spacing on SDT has also been studied and it is likely to occur on the surface with longer, wider and thicker pillars, as well as pillars with cone-like shape and larger hydrophobicity. These results should be useful for a complete understanding of the nanoscale SDT and shed light on the design of smart superhydrophobic surfaces.