Among various architectures of polymers, rings of end-groups free have attracted growing interests due to their distinct physicochemical performances over the linear counterparts which is exemplified by reduced hydrodynamic size and slower degradation. It is key to develop facile methods to large-scale synthesize polymer rings with tunable compositions and microstructures. Recent advances in large-scale synthesis of polymer rings against single-chain dynamic nanoparticles, and the example applications in synchronous enhancing toughness and strength of polymer nanocomposites are summarized. Once there is the breakthrough in rational design and effective large-scale synthesis of polymer rings and the functional derivatives, a family of cyclic functional hybrids would be available providing a new paradigm in developing polymer science and engineering.