SE/KTE series double-step machine is mainly used in the field of waste plastics recycling and filling, one-step modification of waste plastics. The upper step single screw extruder is applied to melt waste plastics, with enlarged feed opening design which is conducive to increase the production capacity, and enlarged screen changer design to improve the filtration efficiency. The lower order twin-screw extruder can add filler, glass fiber, additives, etc. to provide enough mixing, dispersion, modification and enhancement to improve product quality and reduce energy consumption.