SnO2　nanoneedles,　nanorods　and　nanowires　were　synthesized　at　different　temperatures,　and　their　field　emission　properties　were　investigated　in　detail.　On　comparing　the　three　nanostructures　of　SnO2,　we　find　that　the　synthesis　temperature　has　a　prominent　influence　on　the　morphology,　consequently　affecting　the　field　emission　properties,　especially　the　turn-on　field　and　the　emission　current　density.　Among　them,　the　SnO2　nanoneedle　possesses　the　lowest　turn-on　field　of　1.23　V/mu　m　and　the　highest　current　density　2.19　mA/cm(2)　at　3.06　V/mu　m.　The　mechanism　behind　the　influence　of　the　synthesis　temperature　on　the　morphology　and　field　emission　properties　of　SnO2　nanostructures　is　discussed　in　detail.　These　results　can　be　valuable　for　the　application　of　SnO2　nanomaterial　in　the　cathodes　of　field　emission　based　devices.