Abstract: The present disclosure provides a universal preparation method for in-situ growth of a layered double hydroxide (LDH) layer on a substrate surface, and belongs to the technical field of material synthesis. In the present disclosure, an LDH protective layer is grown in situ on a surface of a substrate by means of electrodeposition combined with hydrothermal treatment. Specifically, a seed crystal layer of the LDH is formed on the substrate surface by the electrodeposition, and then obtained LDH seed crystals are crystallized and grown by Ostwald ripening through the hydrothermal treatment. In this way, the LDH protective layer is formed in which an interlayer anion is a nitrate. The protective layer protects the substrate against corrosion. Moreover, since the interlayer anion is the nitrate, the protective layer can be exchanged with other corrosion-inhibiting anions, and is modifiable.