A polystyrene(PS)/nanosilica organic-inorganic hybrid material was prepared from styrene monomer and commercial aqueous silica sol containing large amounts of Si-OH by means of emulsion polymerization. The nanosilica sol was modified by the addition of the reactive coupling agent methacryloxy propyltrimethoxysilane(MPS), and the resulting latex particles were protected by surfactants such as sodium dodecyl sulphonate(SDS), hydroxypropyl methyl cellulose(HMPC), and poly(vinylpyrrolidone)(PVP). The effects of the type of surfactant, the amount of surfactant, and the coupling agent on the shape and stability of the resulting latex particles were investigated. The TEM observation indicates that among SDS, HMPC, and PVP, SDS is the best surfactant. When the content of SDS is 0.5% and the amount of MPS is 7% in the system, the latex with obvious core-shell structure could be obtained. The average diameters of the monodispersed particles range from 182 to278 nm, and the average number of silica beads for each composite are 1325 and 4409, respectively. The FTIR analysis shows that PS was chemically linked to silica through MPS. The thermal gravimetric analysis shows that when there is a higher silica content, the hybrid composites have a better heat resistance.