A core-shell structure polystyrene-polyacrylate emulsion has been prepared, in which acrylic polymer acts as the shell and polystyreneacts as the core, via two stages emulsion polymerization. Acrylicacid is used as the functionalmonomer, of which the carboxyl group at the surface of the film provide hydrophilic property. Three methods are reviewed in this article to improve properties of the film, include searching appropriate content of emulsifier with m in imumgel formation; adjusting the dosage of divinyl benzene( DVB) to increase the internal cross-linking degree of the emulsion particles and adding 1, 6-hexame thylene diam ineasexternal cross-linking agent of the coatings. Through these threem ethods above, the pencil hardness of the coatings can reach 2H and thew ater resistance of the coating is good enough in 48 h without whitening and peeling.