In the global issue of plastic reduction and sustainable development, "recycling" has become a high-frequency term. However, there is not only one form of circular economy. From PET bottles to textile fibers, from high-purity recycling from bottle to bottle to degraded utilization from bottle to clothing, the fate of plastics extends in both closed-loop and open-loop recycling systems. Understanding the differences between these two is the key to understanding the plastic recycling system.