The invention discloses an acrylic acid microgel emulsion having the automatic restoration function and a preparation method thereof, and belongs to the technical field of a modified coating. The acrylic acid microgel emulsion comprises a shell layer and a core, wherein the shell layer includes a shell solution, water, isobornyl methacrylate, butyl methacrylate, alkylphenol polyoxyethylene, sodium dodecanesulphonate and potassium persulphate, and the core includes styrene, lauryl methacrylate, acrylic acid, hydroxyethyl methylacrylate, glycidyl methacrylate, 3-glycidoxypropyltrimethoxysilane, 2,2'-azobis (2,4-dimethyl) valeronitrile and ethanol. The emulsion has the advantages of low VOC discharge capacity and high solid content. The shell layer doesn't crack and the core colloid isn't released when the emulsion is sprayed at the room temperature. When a scratch appears, hot water with the temperature of 80 DEG C is used to wash the scratch, and the shell layer is heated, softened, and collapsed to release the core colloid. The core colloid is heated and softened to gradually fill the scratch, is self-cross-linked, and is hardened, so that the scratch is lightened and disappeared.