Silica nanoparticle/polyaniline composite microspheres (SPCMs) were synthesized in a Pickering emulsion for the first time. The products were characterized by SEM and FTIR. The SPCMs were consisted of a polystryrene core and a silica nanoparticle shell. The average diameter of the SPCMs was about 3.3 μm. A mechanism for the formation of the SPCMs was discussed. The route reported here may be used for the preparation of other novel composite nanostructures.