In recent years, half-metallic materials, an ideal material to fabricate spintronic devices, have attracted intensive research attention.Meanwhile, two-dimensional atomic monolayer materials, such as graphene, BN and other inorganic monolayer, have been widely investigated from both experimental and theoretical standpoints for their novel properties and intriguing applications in nano-electronics.Recent studies suggest graphene nanoribbon can be converted to half-metal by applying an external electric field, or chemically modified with functional groups at two open zigzag-type edges.Theoretical study also showed BN nanoribbon with bared edges also exhibit half-metallic properties.These findings suggest the possibility to synthesize one-dimensional nanoribbon based half-metallic materials.We performed a systemic study on the unpassivated inorganic nanoribbons and some hybrid C-BN nanoribbons using density functional theory method.We find that the unpassivated zigzag edges can lead to spin-splitting of energy band in inorganic nanofibbons, such as BN, AlN, GaN, SiC, and ZnO, and some may exhibit half-metallic properties.Possible edge reconstruction at the unpassivated edges may happen in BN and AlP nanoribbons, which will further curtail their half-metallieities.Upon the hybrid C-BN nanoribbon, the first-principles study suggests that the hybrid C-BN nanoribbons can possess half metallicity with specific heterojunetion structures for the fused edge and within a special range of widths for the graphene and BN sections.In general, the hybrid C-BN nanoribbons can undergo the semiconductor-to-half-metal-to-metal transitions as the width of both graphene and BN nanoribbons increases.The calculated electronic structure of the hybrid C-BN nanoribbons show that dihydrogenation of the boron edge can induce localized edge states around the Fermi level, and the interaction among the localized edge states leads to the semiconductor-to-half-metal-to-metal transitions.Successful fabrication of the hybrid C-BN nanoribbons with half metallicity may open a new synthetic path for the development of low-dimensional spintronic materials.