The invention provides a high-foaming-ratio polylactic acid alloy foaming material. The high-foaming-ratio polylactic acid alloy foaming material comprises, by weight, 100 parts of polylactic resin and 0-30 parts of polyethylene resin. The alloy foaming material is of a closed-cell structure. Polylactic acid/polyethylene blended alloy is prepared through melt blending, crystallization and rheological behaviors of the blend are improved, viscoelasticity of the blended alloy is improved, and high-foaming-ratio closed-cell foam with a composite cellular structure is obtained.