Abstract: The core-shell composite polymer emulsion of poly (ethyl acrylate)/polystyrene was prepared by seeded emulsion polymerization with emulsified monomer. The cover areas of a sodium dodecyl benzene sulphonate molecule adsorbed on latex particles of PEA and PS were measured respectively. The quantitative relationship between the emulsifier supplement and the polymerized monomer and proper monomer feeding rate were determined during seeded polymerization. The stable composite polymer emulsions with various component ratio were successfully prepared. The composite tatex particles in the system are of the inversed core-shell structure.