The spinning temperature of polypropylene staple fiber is high (above 300℃), and the spinning temperature of various specifications of materials varies greatly. Therefore, the selection and control of polypropylene staple fiber temperature is very important. If the spinning temperature is too high, in addition to possible hair breakage, the main manifestation is that the strength of the finished product will be significantly reduced, and the post-stretching will also be abnormal. If the control temperature is too low, in addition to the possibility of hard-end filaments and melt cracks, the tensile properties will be deteriorated, or even cannot be stretched, and the drawing ratio will be forced to reduce, or the drawn filaments will shrink too much, resulting in finished products. The elongation is too large. In addition to empirical observation, the spinning temperature control mainly depends on testing the viscosity average molecular weight of the oil-free yarn. In general, the thermal insulation zone has the greatest impact on polymer degradation. Therefore, changing the temperature in this zone will quickly change the molecular weight of oil-free filaments. Controlling the spinning temperature is one of the keys to the production of polypropylene staple fibers.