The invention discloses inorganic water-based metallic paint and a preparation method thereof. The paint is prepared from raw materials in percentage by weight as follows: deionized water, an anti-freezing agent (ethylene glycol), a film-forming aid (dodecanol carbonate), a bactericide (Rohm and Haas LXE), an organic silicon defoaming agent (Rohm and Haas 505), a leveling agent (Rohm and Haas RM2020), nano titanium dioxide or nano zinc dioxide, sericite powder, nano calcium carbonate powder, potassium trimethylsilanolate, silica sol NM-1020, fumed silica, pearl powder, an emulsion and an associative alkali swelling thickener. The inorganic water-based metallic paint is uniform to spray during construction, the pearl powder is arranged orderly, the color is uniform, the luster of the pearl powder is completely restored, the surface is fine and smooth, and the hand feeling is fine and smooth.