The extruder is composed of feeding section, compression section and metering section. In order to prevent material’s inverse flow, the stage 1 temperature is basically in melting temperature. The temperatures in the three parts gradually increase to make the polymerized substance constantly heated, and transform from vitreous state to viscous flow state in flight channel. When being squeezed into spinning box by screw, the effect of spinning box is still to promote the polymerized substance’s melting chain breakage. Also, the material has same flow path and heat energy absorption in spinning box. Finally, the die head, which is squeezed by metering pump in constant quantification, is formed into fibre through blowing and stretching of high-speed hot air.