The invention provides a foaming material prepared by blending plant straw filled polypropylene / polyethylene. The foaming material comprises the following raw materials in parts by weight: 60-80 parts of polypropylene plastic, 20-40 parts of polyethylene substrate, 1-5 parts of foaming agent, 40-50 parts of plant straw powder, 1-2 parts of coupling agent, 3-5 parts of heat stabilizer and 0.5-1 part of lubricating agent. The preparation process comprises the following steps: preparing the plant straw powder, and then treating the plant straw powder with the coupling agent; evenly mixing the polypropylene plastic, the polyethylene substrate, the foaming agent, the plant straw powder treated by the coupling agent, the heat stabilizer and the lubricating agent; carrying out fusion blending and pelleting on the mixture, and carrying out extrusion molding; and finally, heating the sectional material, adding the foaming agent for mixing, extruding and foaming in an extrusion machine, and cooling to obtain the product, wherein the temperature of the extrusion machine is controlled between 180 DEG C and 200 DEG C. The product prepared by the process in the invention has better bubble form,foaming density and density of the foaming material as compared with the other foaming materials; and simultaneously, the product has excellent impact strength and physical and mechanical properties.