Mn3O4 nanowires were prepared by electrospinning followed by H2 reduction. XRD patterns showed the samples were tetragonal phase with the average grain size of about 24.7 nm. The diameter of Mn3O4 nanowires was about 100 nm and the nanowires were porous ones. The magnetic properties of the samples presented obvious the feature of ferromagnetism at 5 K and a small coercivity. The porous and magnetic features mike that the nanowires can be used as the filtration for the separation of the magnetic-active particles.