Abstract: Polymeric glass modifier having a partially crosslinked structure capable of effectively reducing the surface gloss of a thermoplastic resin, is prepared by (a) emulsion polymerizing an acrylic monomer, an ethylenically unsaturated cyanide compound end, optionally, an aromatic vinyl monomer to obtain a copolymer latex of a linear structure; (b) conducting a crosslinking emulsion polymerization of the resultant linear copolymer latex obtained in step (a) with an addition of the same monomers used in step (a), an acrylamide inter-particle crosslinking agent and an ethylenically unsaturated crosslinking agent to produce a partially crosslinked latex; and (c) coagulating and interparticle crosslinking the partially crosslinked latex obtained in step (b) with an addition of an acid to obtain the polymeric gloss modifier.