The invention discloses a preparation method of high-performance waterborne acrylic resin. The waterborne acrylic resin is prepared from the raw materials of, by mass, 25-35 parts of unsaturated monomers containing hydroxyls, 20-40 parts of hard monomers, 20-40 parts of soft monomers, 8-15 parts of unsaturated carboxylic acid, 3-5 parts of an initiator, 0.5-2 parts of an organic silicone modifier,0.5-1.5 parts of a chain transfer agent and 80-90 parts of a solvent. The preparation method comprises the steps that colorless and transparent acrylate prepolymers with the hydroxyl content of 2.5 mmol / g and the solid content of 60+ / -1% is synthesized by solution copolymerization, and the high-performance waterborne acrylic resin is obtained through a 'salt forming method'. According to the preparation method, the organic silicone modifier is introduced to the acrylic resin to improve the water resistance, heat resistance and chemical resistance performance of the acrylic resin, a simple method, cheap raw materials which are convenient to obtain and conventional equipment are used for preparing the waterborne acrylic resin with good performance, the glossiness of a product is high, the drying speed is fast, the mechanical performance is excellent, water resistance, weather resistance and solvent resistance are good, and the coating demands of the majority of workpieces are met.