Since rubber was applied in people’s normal life, researchers have started to exploit the rubber reinforcing techniques and the relative mechanism. Developing high-effective, simple and economical reinforcing methods and fillers are the emphasis of rubber industry, technology and science. In this paper a rubber ideal filler (IF) is shown. This IF is a kind of composite with core-shell structure which was synthesized by seeded emulsion polymerization. It used styrene (St), polybutadiene oligomer (PBD) as monomers and divinyl benzene (DVB) as cross-linking agent. The effect of the amount of cross-linking agent, concentration of emulsifier and initiator on the stability of the emulsion was studied. The morphology of the latex particles with core-shell structure was characterized by high resolution SEM (ESEM) and DSC (Tg). The results showed that cross-linking polymeric particles exhibited strong reinforcing effect on styrene-butadiene rubber (SBR).