A microbubble creating method using a forming machine for creating microbubbles by: installed a microbubble generating member in a mold, feed screw or barrel for enabling a perforated tip of the microbubble generating member to be surrounded by the applied fluid polymer so that when a high pressure high temperature gas is delivered through the perforated tip of the microbubble generating member, microbubbles are created with well mixed with the fluid polymer, and the expected foamed polymer product is thus obtained after cooling.