Magnesium hydroxide film with smooth surface and preparation method thereof

The invention discloses a magnesium hydroxide film with a smooth surface and a preparation method thereof. The preparation method comprises the following steps: jointly constructing an electrochemical reaction system by using a to-be-conductive metal substrate serving as a working electrode, a counter electrode and an electrolyte, wherein the electrolyte comprises magnesium salt, xanthan gum, glucose, glycerol and lactic acid; and electrifying the electrochemical reaction system, and preparing and forming the magnesium hydroxide film with a smooth surface on the metal substrate to be subjected to electric conduction by adopting an electro-deposition method. The lactic acid is added into the electrolyte, so that the pH value of the electrolyte can be stabilized by using the weak ionization characteristic of the organic acid, the branched chain decomposition and loss of the structure induction effect of a structure inducer represented by xanthan gum under the low pH condition are avoided, and meanwhile, the ads