TiO2-coated polystyrene nanoparticles were prepared in a simple way. First, functional PS particles were synthesized by copolymerizing one kind of polymerizable surfactant with styrene. Then the stable dispersions of polystyrene nanoparticles were used as templates, and polystyrene nanoparticles were coated with titania by in situ hydrolysis of tetra-n-butyl titanate (TBT). No surface treatment and centrifugation/redispersion cycle process were needed during the whole experiment. Isolated PS spheres with uniform coatings of titania were obtained when water concentration was lower than a certain level.