Abstract: PMMA with high adsorption capacity for supercritical carbon dioxide is selected as the matrix material and foamed by supercritical CO₂ foaming technology. The influences of saturation and foaming stage parameters and CO₂ adsorption capacity on the structure parameters of the PMMA foam are studied. The results reveal both the low-temperature and high-pressure can increase the adsorption capacity of CO₂, and that the mass fraction of CO₂ in PMMA increases from 21.59% to 35.72%.After the PMMA with CO₂ of 35.72% is foamed at 40 ℃ for 30 s, we can obtain the PMMA nano-cellular foam with the uniform cell size of 35.9 nm and cell density of 1.57×1 015.