A convenient fabrication technique for samarium hexaboride(SmB_6) nanostructures(nanowires and nanopencils) is developed, combining magnetron-sputtering and chemical vapor deposition. Both nanostructures are proven to be single crystals with cubic structure, and they both grow along the [001] direction. Formation of both nanostructures is attributed to the vapor-liquid-solid(VLS) mechanism, and the content of boron vapor is proposed to be the reason for their different morphologies at various evaporation distances. Field emission(FE) measurements show that the maximum current density of both the as-grown nanowires and nanopencils can be several hundred μA/cm~2, and their FN plots deviate only slightly from a straight line. Moreover, we prefer the generalized Schottky-Nordheim(SN) model to comprehend the difference in FE properties between the nanowires and nanopencils. The results reveal that the nonlinearity of FN plots is attributable to the effect of image potential on the FE process, which is almost independent of the morphology of the nanostructures.All the research results suggest that the SmB_6 nanostructures would have a more promising future in the FE area if their surface oxide layer was eliminated in advance. A convenient fabrication technique for samarium hexaboride (SmB_6) nanostructures (nanowires and nanopencils) is developed, combining magnetron-sputtering and chemical vapor deposition. Both nanostructures are proven to be single crystals with cubic structure, and they both grow along the [001] direction . Formation of both nanostructures is attributed to the vapor-liquid-solid (VLS) mechanism, and the content of boron vapor is proposed to be the reason for their different morphologies at various evaporation distances. Field emission (FE) measurements show that the maximum current density of both the as-grown nanowires and nanopencils can be several hundred μA / cm ~ 2, and their FN plots deviate only slightly from a straight line. Moreover, we prefer the generalized Schottky-Nordheim (SN) model to comprehend the difference in FE properties between the nanowires and nanopencils. The results reveal that the nonlinearity of FN plots is attributable to the effect of image potential on the FE proce ss, which is almost independent of the morphology of the nanostructures. All the research results suggest that the SmB_6 nanostructures would have a more promising future in the FE area if their surface oxide layer was eliminated in advance.