We study thermal annealing-driven surface sealing of polymer hollow particles with a different surface property. Use of phase separation between polystyrene (PS) solid particles incorporated with sulfonate (-SO3-) group and decane allows their transformation into hollow particles with an opening on the surface. Control of the phase separation enables us to tune the structure (outer and inner diameters, and size of the opening) of the hollow particles. While thermally annealed at a temperature above T-g of the polymer, structural change of the hollow particles is experimentally observed and theoretically analyzed. The results demonstrate that the change in the surface property of the hollow particles due to the incorporation of the -SO3- group can have a direct impact on their sealing behavior and surface-sealed structure.