A　series　of　GaN　thin　films　were　prepared　by　pulsed　laser　deposition　at　different　deposition　pressure　on　n-type　Si(100)　substrates.　The　field　emission　measurement　results　show　that　the　turn-on　field　Eon　of　GaN　films　is　increasing　with　the　deposition　pressure　increasing,　and　the　FN　plots　show　a　linear　relationship　in　the　high-field　region　for　all　the　samples,　suggesting　that　the　emission　current　originate　from　a　quantum　mechanical　tunneling　process.　GaN　thin　film　has　the　best　FE　characteristics　with　the　lowest　E-on　of　0.95　V/mu　m　at　0.1　Pa,　and　largest　current　density　of　28　mu　A/cm(2)　at　the　field　of　3　V/mu　m.　GaN　film　structure　and　surface　morphology　were　characterized　by　X-ray　diffraction　and　atomic　force　microscopy,　respectively.　The　diffraction　peak　of　the　(002)　plane　of　the　wurtzite-type　hexagonal　GaN　is　observed.　When　deposition　pressure　is　larger　the　amorphous　thin　film　can　be　obtained,　and　the　field　emission　properties　become　deterioration.　Therefore,　the　deposition　pressure　is　essential　to　enhance　field　emission　properties　of　GaN　thin　films,　which　is　through　appropriate　regulation　of　crystal　structure　and　surface　morphology　controlling.