The blending of polymer with nanoparticle is an appealing strategy to create new functional polymer nanocomposites. And in general, different nanoparticles will vest polymers with different properties. Among all the nanoparticles, polyhedral oligomeric silsesquioxane (POSS) and fullerene (C60) have unique structures and fascinating properties, so they have attracted extensive attention in the field of polymer nanocomposites and endow polymers with special functions. In order to create new nanoparticle for the renforcement of polymers, herein, we covalently linked POSS and C60 to obtain POSS-C60 Janus particle. The synthesis is simple and could be easily scaled-up to obtain mono-adults of POSS-C60. When blending POSS-C60 with polystyrene (PS), which could exhibit better reinforcement of both mechanical properties and thermal stability on PS nanocomposites compared with pristine POSS, C60 and POSS/C60 (which means of phycical blends of POSS amd C60). Besides, POSS-C60 could be used as compatibilizer for immiscible PS/polymethyl methacrylate (PMMA) blends. It was found that the domain sizes of dispersed PMMA phase decrease in PS matrix, and the mechanical properties of PS/PMMA blends were largely enhanced by adding a small amount of POSS-C60. More importantly, POSS-C60 tends to locate at the PS/PMMA interfaces. Our studies provide not only some new ideas for the preparation of polymer nanocomposites with novel particle shapes and unique properties, but also for precisely controlling the positions of nanoparticles in polymer matrix, which is great importance for the preparation of high-performance polymer nanocomposites.