Abstract: Lanthanum hexaboride field-emitter arrays(LaB6 FEAs) with tip structures are fabricated by oxygen plasma oxidation-etching method. The field emission characteristics are studied in a conventional diode test cell in vacuum system. LaB6-FEAs exhibit a much lower turn-on field of 7 V·μm-1 due to its lower work function of 2.6 eV. The Fower-Nordheim plot obtained from the current-voltage characteristic is found to be nearly linear in accordance with the quantum mechanical tunneling phenomenon. In addition, oxygen plasma oxidation-etching method is also compared with argon-oxygen plasma etching method and electro-chemical etching method, which indicates that oxygen plasma oxidation-etching method is a very promising fabrication technique for the preparation of LaB6-FEAs.