In recent years, economics, technology, and resin availability have all combined to cause a dramatic rise in the use of high density polyethylene (HDPE) films throughout the plastics industry. Not only has the extrusion technology improved, but in addition the resin producers have developed resin structures and formulations which permit the production of an extraordinarily wide range of films for a wide range of usages [1]. As the result, HDPE film extrusion lines have been required to produce quality films at a rate that was unattainable a few years ago. Demands for better film quality and greater production flexibility have created the need for continuing improvements on the various components of the entire line. Although bubble cooling and web handling have improved in mechanical design, the major breakthrough lies in the screw and die designs, both of which are the essential parts of the entire blown film process. A proper screw design tailored for HDPE makes it possible to deliver the homogeneous melt at high throughput rate and within the temperature confinement of that particular resin. A good die design provides a uniform molten polymer with reasonable pressure drop. Die design technology is now available for tubular die to effect more optimized productivity and product quality. In this paper, new techniques are presented for designing the tubular die, and experimental works on HDPE screw are discussed.