A series of Fe3O4/MgO superlattices, with MgO fixed at similar to 20 Angstrom and Fe3O4 varied from 10 to 80 Angstrom, are fabricated on MgO(001) and related substrates with an oxygen plasma assisted molecular beam epitaxy (MBE). The samples were analysed by in situ reflection high-energy electron diffraction (RHEED), ex situ X-ray diffraction (XRD), and ft-ray absorption spectroscopy (XAS). It is observed that these oxide films have single crystalline quality along the same orientation as the substrates, even for Fe3O4 as thin as about one unit cell. Sharp interfaces between layers were obtained by appropriate arrangement of cations during the growth. The interfacial strain originated from the lattice misfit between the parent materials and substrate is accommodated by a tetragonal distortion of Fe3O4. This effect results in an extremely stable growth mode of these superlattices.