Permanent　magnetic　nanocrystalline　Sm5Co19Hf0.4　alloy　and　Sm5Co19Hf0.4CNTs0.4　alloy　with　high　room-temperature　coercivity　were　prepared.　The　microstructure,　crystal　structure　and　magnetic　properties　were　studied.　The　results　show　that　the　mixed　doping　of　Hf　elements　and　CNTs　does　not　lead　to　phase　decomposition　of　Ce5Co19　type　structure,　while　it　results　in　fine　grains　and　uniform　distribution　of　the　microstructure.　Energy　Dispersive　X-ray　Spectrometry　(EDX)　analyses　confirm　that　CNTs　move　into　grain　boundaries　of　the　nanocrystalline　Sm5Co19Hf0.4CNTs0.4　alloy,　which　can　improve　the　coercivity　of　the　nanocrystalline　Sm5Co19　alloy　for　the　grain　boundary　pinning　effect.　Rietyeld　refinement　show　that　Hf　comes　into　the　Sm　vacancy,　thus　decreasing　the　lattice　parameters　and　increasing　the　axial　ratio　c/a,　which　further　enhance　the　magnetocrystalline　anisotropy,　and　strengthen　the　coercivity　of　nanocrystalline　alloy.　The　results　of　the　study　can　promote　the　design　of　Sm-Co　alloy　with　high　magnetocrystalline　anisotropy　and　intrinsic　coercivity.