Provided are an acrylic copolymer composition, a method for preparing an acrylic copolymer, and a vinyl chloride resin composition including the acrylic copolymer. The acrylic copolymer composition includes 5-15 wt % of a crosslinking agent and an alkyl acrylate monomer constituting an alkyl acrylate crosslinked polymer and 85-95 wt % of methyl methacrylate and at least one monomer selected from the group consisting of alkyl acrylate and alkyl methacrylate. Addition of the acrylic copolymer to the vinyl chloride resin composition enhances the foaming property of the vinyl chloride resin. Combination of the acrylic copolymer with an impact modifier further enhances the impact strength of the vinyl chloride resin.