PURPOSE: To obtain the titled fiber having uniform internal structure and good surface property, keeping high strength and modulus of the fiber, by extruding concentrated sulfuric acid dope of a poly-p-phenylene terephthalamide polymer into a coagulation bath under specific condition.

CONSTITUTION: A poly-p-phenylene terephthalamide polymer is dissolved in a concentrated sulfuric acid having a concentration of 95W100wt%. The obtained dope is extruded into an active gas atmosphere having an oxygen concentration of ≥25vol% through a circular orifice having a diameter of 0.03W0.10mm at an extrusion rate of ≥20m/min, preferably ≥m/min, and then introduced into a coagulation bath to obtain the objective fiber. The gap between the tip of the spinneret orifice and the surface of the coagulation bath is preferably ≥1mm, especially 3.0W20mm.