A nano-carbon material field emission cathode plate is prepared by an oxidation-reduction reaction, which includes immersing a substrate having a first metal layer thereon in a solution of a second metal salt with a nano-carbon material dispersed therein. A difference between the two standard redox potentials of the first metal and the second metal is so great that ions of the second metal in the solution are reduced to elemental metal while the first metal is oxidized, and thus a layer of the second metal is formed on the first metal layer with the nano-carbon material partially embedded in the second metal layer.