In this paper, a novel process was presented to synthesize monomodal and bimodal polymer brushes by optimizing living anionic polymerization (LAP) and Ugi four-component reaction (Ugi-4CR). As a remarkable tool, LAP provides an efficient entrance to synthesize the di-endcapped polymer chains. Consequently, the α-terminal silicon oxide group enables polymer chains to be anchored on the surface of nanosilica particles, while the ω-terminal amino group enables Ugi-4CR to be used in the preparation of the multimodal brushes. Through the regulation of the graft density during the “grafting onto” process, the concentration of the amino groups on the nanoparticles involved in the Ugi reaction can be adjusted, and by changing the feeding ratio of aldehyde-terminated polystyrene, the efficiency of the Ugi reaction can be controlled, thereby achieving the synthesis of monomodal and bimodal polymer brushes. After precisely characterizing those polymer brushes, a flexible approach may be preliminarily raised for tuning the topological structure of the polymer chains on the nanoparticle surfaces.