A facile, flexible and large-scale technique was proposed to prepare a CuO-CNT 3D-network composite with the aid of electrostatic interactions in aqueous solution. The composite greatly improves the electrochemical performance. At a rate of 0.1 C, the cycling discharge capacity of the optimal composite is more than 2.3 times of that of unmodified mesoporous CuO nanosheets as the active material in an anode after 40 cycles.