Abstract: Narrowly-distributed silica-polyacrylonitrile(PAN) core-shell composite nanoparticles were prepared via emulsion polymerization using 3-(trimethoxysilyl)propyl methacrylate-modified silica nano-particles as the seeds. Dynamic light scattering, Fourier transform infrared spectroscopy, transmission electron microscopy and scanning electron microscopy were used to characterize the size, composition, structure and morphology of nanoparticles. The effects of the feeding mode of surfactant sodium dodecyl sulfate (SDS), the reaction temperature and the introduction of crosslinker on the synthesis of the composite nanoparticles were investigated. Results show that the structure of the silica-PAN composite nanoparticles is core-shell. The semi-continuous feeding of SDS can efficiently inhibit the production of secondary PAN nanoparticles during the emulsion polymerization. When the initial surfactant amount increases, the supplement rate of surfactants increases, or the reaction temperature decreases, the size of silica-PAN composite nanoparticles decreases. Silica-PAN composite nanoparticles with relatively smooth surfaces can be obtained via reducing the reaction temperature or introducing crosslinker.