The pre-spinning positions of polyester filament mainly include chip drying, melting, spinning, cooling, and winding. In addition, it also includes auxiliary unit heat medium system, blowing system and oiling agent system. This post uses a screw extruder to melt and mix the dried and qualified slices, transfer them to the spinning box insulated with heat medium, and measure them by a metering pump. The melt passes through the filter layer at a precise flow rate and a higher pressure, and is sprayed. The silk holes are sprayed out of silk, and in the spinning window, after being uniformly cooled and solidified by constant temperature and humidity cooling air, the wet is oiled, and the silk barrel is wound on the winding machine.