The invention relates to a preparation method for preparing high-strength polypropylene foamed beads (EPP) with low irradiation intensity. The method comprises the following steps: 1, blending and granulating co-polypropylene with the melting point lower than 150 DEG C, glycidyl methacrylate (ether) and a stabilizer in a parallel twin-screw extruder; irradiating by high-energy electron rays; thenadding carboxyl-, or hydroxyl-, or amino-terminated long-chain structure substance, or carboxyl, or hydroxyl, or amino substance with two or more functional groups at the tail end as a chain extenderand other functional additives; extruding again by using double screws, carrying out water-cooling bracing granulation, drying, and foaming by using a physical foaming agent intermittent kettle methodto obtain the high-melt-strength polypropylene foamed beads (EPP). The processing process is green and pollution-free, and the structure of the materials are controllable; the random polypropylene foam material prepared by the method is low in VOC (volatile organic compound) content, pressure-resistant, buffering and heat-insulating, has excellent high strength, high resilience, shock absorption,energy absorption, heat resistance and oil resistance, is easy to mold and form, and can be widely applied to the fields of military industry, automobiles, buildings, children toys, food packaging materials, household appliances and the like.