This production line adopts a fully automatic control system, where all raw materials are manually poured into their respective raw material silos. Under the control of a computer, they are automatically weighed and measured according to the specified formula and transported to the material silo above the mixing system for storage. When the mixer requires materials, they are discharged into the mixer. The materials mixed by the high-speed heating mixer and cooling mixer are discharged into the U-shaped hopper below the cooling mixer to achieve continuous feeding to the pelletizing extruder.