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We have investigated the nucleation and crystallization processes of molten silicon (Si) on SiO2 substrates by performing molecular dynamics (MD) simulations based on the modified Tersoff potential parameters. A heat flow that leads to a steady fall of the local temperature in the molten Si is achieved by determining the atomic movements with the combination of Langevin and Newton equations. Good agreement is reached between the predictions of temperatures based on the kinetic energies and the velocity distributions of atoms at local regions. The results of simulations revealed that the (111) plane of the Si nuclei formed at the surface was predominantly parallel to the substrate of MD cell. The surface energies of the (100), (110), and (111) planes of Si at 77 K were calculated to be 2.27, 1.52, and 1.20 J∕m2, respectively, and they were in good agreement with the experimental results. The lowest value of surface energy, 1.20 J∕m2, for the (111) plane at 1700 K was obtained under the condition of elastic hard wall. The surface energy anisotropy is expected to be a driving force for the preferential surface nucleation of Si(111) at the surface.