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Ferroferric oxide nanotubes were prepared by calcining and reducing the composite nanofiber precursors fabricated by electrospinning. Influences of the electrospun parameters (PVA concentration of solution, applied voltage and collector distance) on the preparation of the composite nanofiber precursors were discussed. The structural properties of the obtained nanotubes were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The formation mechanism of the Fe3O4 nanotubes was investigated through the nonequilibrium heat-treatment procedure. Furthermore, the magnetic property of Fe3O4 was measured using a vibrating sample magnetometer. Results reveal that the tubes show a uniform and continuous morphology, whose outer and inner diameters are about 100 nm and 50 nm, respectively. Fe3O4 possesses saturation magnetization (Ms) of 54.2 A·m2/kg, coercivity (Hc) of 215×79.6 A/m and remanent magnetization (Mr) of 12.8 A·m2/kg, respectively.