We　adopt　thermal　coating　method　to　coat　the　carbon　nanotubes　(CNT)　paste　on　the　nickel　wire　to　fabricate　linear　cathodes,　of　which　the　field　emission　properties　are　measured　in　the　cylinder　glass　tube.　The　SEM　images　indicate　that　there　is　a　homogeneous　layer　of　CNT　on　the　surface　of　linear　cathode;　the　field　emission　measurement　suggests　that　our　cathode　shows　superior　properties　compared　with　traditional　field　emission　cathodes.　The　linear　cathodes　can　be　turned　on　with　an　electric　field　as　low　as　0.15　V/μm,　and　the　anode　voltage　is　as　low　as　2280　V　at　the　total　current　of　4　mA.　The　highest　brightness　measured　in　vacuum　reaches　14000　cd/m2.