A method for preparing a multi-ion embedded supercapacitor with electrochemical alkaline activation. A simple and rapid electrochemical alkaline activation method is employed to perform activation or deactivation processing on a transition metal hydroxide containing cobalt or nickel to realize intelligent regulation and control of the hydroxide electrode materials to storage capacity of various metal cations, and is applied to an ion embedded supercapacitor. Provided is a universal method capable of improving storage capacity of electrode materials of an ion embedded supercapacitor, and the range of application of the transition metal hydroxide electrode materials is further widened in the field of energy storage.