The invention relates to a preparation method of a high-performance water-soluble high-solid low-viscosity acrylic resin. In a compound solvent system, a continuous-process free radical solution polymerization is adopted for preparing the acrylic resin, and the resin is endowed with water solubility. Modification is carried out by utilizing a tertiary carbonate ester, and a large branch structureis introduced, so that the intermolecular force is reduced, the resin viscosity is reduced, and the high-solid resin has lower viscosity. Through a tertiary carbonic acid group, the water resistance and the alcohol resistance of a paint film are remarkably increased, the performances such as the toughness and the impact resistance of the paint film are remarkably improved, and the influence on thehardness of the paint film is less. According to the preparation method of the high-performance water-soluble high-solid low-viscosity acrylic resin provided by the invention, organosilicone is usedfor modifying the acrylic resin, so that the performances such as humidity resistance and corrosion resistance of the paint film are improved; an amino resin is used as a curing agent for directly preparing a water-based amino acrylic acid baking paint, so that the performances such as hardness, fullness, water resistance, alcohol resistance and salt tolerance of the paint film are good, and the paint film is suitable for industrial coating in the industries of automobiles, bicycles, agricultural machinery and the like, an can be used for coating in the industries of fishing rods, wine bottles, dining tables and other industries with a certain humidity resistance and pollution resistance requirements.