Abstract: A method for extrusion molding of a self-locked nut employs molds to perform the following steps in a nut forming machine. The steps comprise: slug cutting off step for preparing a slug; trimming step for trimming the configuration of the slug to become predetermined size; flange pre-formation step for forming a flange prototype at one end face; flange adjusting and tooth portion forming steps for further adjusting the flange prototype of slug to be predetermined length and on the periphery of flange to form the straight row of tooth portion axially; punching step for forming a through hole axially on the slug after above steps and forming threads inside the through hole.