A　variety　of　morphologies　and　dimension　of　ZnO　nanomaterial　was　synthesized　using　hydrothermal　methods.　The　structure　and　morphologies　of　ZnO　products　were　characterized　by　X-ray　diffraction　(XRD)　and　scanning　electron　microscopy　(SEM)　respectively.　The　impact　of　the　growth　of　ZnO　material　factors　was　analyzed　and　the　mechanism　of　growth　was　discussed　too.　The　characteristics　of　field　emission　for　a　variety　of　morphologies　ZnO　array　were　studied.　The　experimental　results　show　that　field　emission　performance　of　nano-tube　ZnO　was　the　best　in　all　of　various　structure　of　ZnO　nanomaterial.　The　maximum　current　density　reached　0.2mA/cm2　and　its　turn-on　field　was　2.5V/μm.　The　results　provide　a　feasible　method　for　improving　field　emission　properties　of　ZnO　nanomaterial.