The invention discloses an industrially-applicable method for preparing a polymer foamed material by using supercritical fluid technology, which comprises the following steps: 1) forming a polymer raw material to be foamed into raw blanks by melting, blending and cooling; 2) placing the raw blanks in a container, charging supercritical fluid into the container, and allowing the raw blanks to swell and the supercritical fluid to permeate into the raw blanks; and 3) initiating nucleation and foaming by controlling pressure relief rate and obtaining the closed micro pore polymer foamed material with uniform pore diameter and adjustable pore density. According to the invention, the process is simple, the production process is clean and environment-friendly, the efficiency is high, and the prepared foamed material has high mechanical performance and can be used in fields of transportation vehicles, building materials, packages and the like.