The invention discloses a single-component quick air-drying water based paint resin and a preparation method thereof. The water based paint resin comprises (methyl) acrylate, (methyl) acrylic acid, hydroxyl-containing acrylic acid, styren, tertiary carbonic acid vinyl ester, a chain transfer agent, an initiator, a low-aliphatic chain siloxane monomer, a solvent and an air-drying resin solution. The preparation method comprises the steps of adding (methyl) acrylate, (methyl) acrylic acid, hydroxyl-containing acrylic acid, styrene, tertiary carbonic acid vinyl ester, the chain transfer agent, the initiator and the low-aliphatic chain siloxane monomer into the solvent, mixing to form a solution, conducting a polyreaction, neutralizing into salt with an alkaline solution after the polyreaction, controlling a range of a PH value to be 6-9, adding water and the air-drying resin solution, and finally forming the single-component quick air-drying water based paint resin. The water based paint resin prepared by the preparation method can realize a purpose of quick drying.