Solid and hollow nanospherical chains of magnetite with different diameters and diameter/length aspect ratios were prepared by chemical precipitation method in magnetic field. By transmission electron microscopy, x-ray diffraction, magnetometry, and Mössbauer spectroscopy, it was found that the application of magnetic field during precipitation induced the formation of spherical chain structures and simultaneously caused the change of hyperfine field and isomer shift of the octahedral sublattice spectra, implying that the nanospherical chains were not chains of nanoparticles formed simply by magnetostatic attraction. In addition, the solid and hollow nanospherical chains with the same diameter of spheres exhibited slight variation of isomer shift and sublattice hyperfine field, while there were the dramatic changes when the diameter of hollow nanospherical chains is down to 100nm.