This work described a straightforward synthetic route to fabricating polymer/silica hybrid particles with controllable architectures and their advantages as abrasives. The poly(vinylpyrrolidone)-modified and divinyl benzene cross-linked polystyrene (PS) cores were synthesized via a developed soap-free emulsion polymerization, and the outer dendritic-like mesoporous silica (D-mSiO(2)) shells were coated onto the cores using an oil-water biphase approach combined with a selective removal of hexadecyltrimethylammonium bromide templates. The resulting core/shell PS/D-mSiO(2) samples were characterized by SEM, TEM, XRD, FTIR, and nitrogen adsorption/desorption, offering comprehensive information on the composition, structure, morphology, pore size, shell thickness, and surface area. The pore size of D-mSiO(2) can be controlled within the range of 3-9 nm by varying the upper oil phases, which serve as swelling agents to enlarge the mesochannels. The PS/D-mSiO(2) particles can be used as novel polishing abrasives and present superior surface quality (0.16 +/- 0.02 and 0.26 +/- 0.03 nm of root-mean-square roughness) compared to the commercial solid SiO2 ones (0.54 +/- 0.05 nm). Moreover, the PS/D-mSiO(2) hybrids with an enlarged pore size result in an inferior structural stability, which is important for final surface finish and removal rate. The presented results provide not only a strategy for preparing PS/D-mSiO(2) core/shell particles with tunable pore sizes, but also a regulation that can be applied to prepare other core/shell hybrids with dendritic-like mesosilica shells.