The extrusion die machine head for steel-plastic composite pipe using preforated steel pipe as skeleton includes transion body, outer die inserted into the transion body, compressino body which and outer die are formed into channel for molten plastics and mouth die connected with compression body. It is characterized by that said compression body is a radially adjustable component, and core die portion is passed through the outer die and set in it, and said core die portino can be divided into three stages, including leading-in core die positioned at leading-in side of perforated steel pipe, matched with inner diameter of steel pipe and formed into reversed blocking for molten plastics, sizing core die positioned at forming side of composite pipe and matched with inner diameter of the composite pipe and plastics-guiding core die from molten plastics channel outlet to output of mouth die. |