Nanocrystalline　diamond　(NCD)　films　were　synthesized　on　the　silicon　substrate　with　diameter　of　10　cm　by　microwave　plasma　enhanced　chemical　vapour　deposition　using　CH4　and　H2　as　the　reactant　gas.　The　film　composition　and　performance　were　characterized　by　X-ray　diffractometry,　Raman　spectroscopy,　scanning　electron　microscopy　and　atomic　force　microscopy,　respectively.　The　results　show　that,　the　average　grain　size　of　the　film　is　about　13.8　nm,　the　maximum　thickness　can　reach　10.8　μm　and　the　surface　roughness　is　11.8　nm.　The　Raman　spectrum　is　the　typical　characteristic　peak　shape　of　nanocrystalline　diamond　films,　and　the　field　emission　properties　were　measured　under　high　vacuum　conditions.　©,　2014,　Zhongguo　Youse　Jinshu　Xuebao/Chinese　Journal　of　Nonferrous　Metals.　All　right　reserved.