The EPS to EPS circular recycling system consists of fully automatic loss-in-weight feeding system, twin-screw extruder, cooling single-screw extruder, screen changer, melt pump, underwater pelletizing, coating and fully automatic packaging system. EPS waste crushed by cold pressing or EPS grinding powder after hot melt grinding can be fed into the twin-screw extruder through the automatic feeding system. The material entering the extruder becomes molten by absorbing the heat from the barrel and the mechanical energy generated by the twin-screw shear. At this time, the pentane blowing agent is injected in the middle of the twin-screw, and the molten material mixed with the blowing agent enters the cooling single-screw after being fully mixed by the twin-screw. After the molten material in the cooling single screw is cooled to a suitable temperature, it passes through the screen changer to filter out the impurities that may be contained in the EPS waste, and then enters the melt pump. The melt pump will provide stable pressure and flow for the next underwater pelletizing. After the material enters the underwater cutting system, it quickly condenses and wraps the pentane blowing agent inside, and then the particles containing the pentane blowing agent enter the dehydration system, and then pass through the vibrating screen to screen out particles of different sizes, and the finished particles will be sent by air. The system is sent to the coating system to apply fluorine coating agent, and the coated beads are sent to the automatic packaging system through the air conveying system for packaging. The system recycles EPS waste and makes EPS expandable beads, which share the same purpose as the original EPS beads for a circular economy.