The invention discloses an electrochemical capacitor and electro-adsorption desalination electrode material, which is formed by the combination of nano nickel oxide and nano carbon materials. The preparation method of the electrochemical capacitor and electro-adsorption desalination electrode material comprises the steps of: 1, preparing a nickel salt aqueous solution; 2, mixing the nickel salt aqueous solution with the nano carbon materials; 3, preparing nanocarbon/nickel oxide composite powder; 4, and preparing an electrode. The electrochemical capacitor and electro-adsorption desalination electrode material obtains large capacitance by utilizing oxidation-reduction property of the nano nickel oxide, is high in conductivity, high in specific surface area and high in utilization rate of specific surface area, endows the electrode with high capacitance of capacitor and energy density, has good charging-discharging repeatability, is easy to implement technological parameter control, is even to coat the nano carbon with the nano nickel oxide, and is suitable for industrialized mass production; and the prepared nickel oxide electrode is small in expansion and high in specific capacity, and has good charging-discharging performance, excellent inorganic ion electro-adsorption performance, long service life, and very high practical value.