The invention provides a high-strength water-soluble powder coating, which is composed of the following components, and the content of each component is expressed in parts by weight: 30-40 parts of epoxy quaternary ammonium sulfonate film-forming polymer, epoxy silsesquioxane 10-15 parts, 10-15 parts of bentonite, 1-3 parts of rare earth polishing powder, 2-6 parts of defoamer, 1-3 parts of dispersant, 2-5 parts of film-forming aid. The invention also discloses a preparation method of the high-strength water-soluble powder coating. Compared with the common solvent-based coatings in the prior art, the high-strength water-soluble powder coating disclosed by the present invention does not contain organic solvents, has better safety, is more environmentally friendly, and has excellent adhesion, film-forming properties, lubricity, and gelation properties. Excellent performance, chelating property, dispersibility, anti-friction property, strength and thickening property, and more significant decorative effect.