Abstract: Polystyrene/silica (PS/SiO2) coreshell nanoparticles (CSNs) were synthesized using nanosized spherical polyelectrolyte brushes (SPBs) as templates by solgel method. SiO2 hollow microspheres were obtained after removing PS cores by solvent. The SPBs consisting of poly(acrylic acid) (PAA) chains covalently attached densely onto the surface of PS cores were prepared by photoemulsion polymerization. Following the Stber method, a uniform SiO2 shell was formed on the surface of PS core using SPBs as templates. The PS/SiO2 CSNs display pHsensibility due to the existing of PAA chains in the periphery of nanoparticles. The SiO2 hollow microspheres prepared by removing of PS cores with chloroform show narrow size distribution. This approach opens a new way to prepare organic/inorganic hybrid coreshell and hollow nanoparticles for broad applications such as drug delivering.