In order to improve the recycling value of waste hard alloy，Cobalt nanowires were synthesized by a magnetic-field-assisted method from acid leaching solution of waste hard alloy. The morphology and thermal stability of cobalt nanowires were tested. The experiments showed that the external magnetic field is the key factor to the morphology of products. With external magnetic field，the cobalt nanowires with an average length of 40 μm and diameter of 500 nm were synthesized.Meanwhile under the same preparation conditions but without external magnetic field，the spherical cobalt particles with no significant arrangement were prepared. When the temperature was less than 225.0 ℃，the cobalt nanowires prepared by this method had good air thermal stability. The study would not only improve the recycling value of waste hard alloy and stimulate the development of recycling economy of cobalt resource，but also have important theoretical basis and practical significance for guiding the preparation and applications of one-dimensional magnetic metal nanowires，especially cobalt nanowires.
