In this paper, we have successfully prepared submicronsized snowman-like polystyrene (PS) particles by radiation-induced seeded emulsion polymerization at room temperature. The monodispersed crosslinked PS particles with an average size of 358 nm acted as seed particles. The influence of polymer/monomer weight ratio on the morphology was studied. The results showed that snowman-like PS particles could be fabricated in high yield about 90% when the polymer/monomer weight ratio was 0.2:1.