Fe-filled BN nanocables with intermediate C layers were fabricated. Complete phase separation between C and BN was distinguished using electron energy loss spectroscopy (EELS) measurements and high-resolution transmission electron microscopy (HRTEM) images by the characteristics of well-ordered BN layers and turbostratic C ones. A two-step growth model is proposed for the formation of this remarkable structure. The idea of introducing intermediate C layer, overcoming the wetting restriction of BN surface, may be employed for fabrication of BN nanocables filled with other metal cores.