The invention relates to a manufacture method for a double-spiral line HDPE pipe, which is characterized in that by utilizing self the residual heat of an HDPE round pipe, and by making use of two extruding rollers which are provided with grooves, are symmetrically arranged on a double-spiral line extruding and setting device installed outside the head of a plastic extruder and can rotate along the HDPE pipe axis, the invention synchronously extrudes the HDPE round pipe to cause two spiral lines to be synchronously formed on the outer surface of the HDPE round pipe, and the HDPE round pipe is manufactured into a double spiral line HDPE pipe through vacuum cooling setting. The invention fully utilizes the self heat of the HDPE round pipe, and saves the energy; double spiral lines on the HDPE round pipe are synchronously formed with a pipe body basically, are not easy to fall off, and have stable quality.