Poly (butylene adipate-co-terephthalate) (PBAT) foams display serious shrinkage problems when supercritical CO 2 is utilized as the blowing agent. In this work, a series of fully biodegradable PBAT/polybutylene succinate (PBS) foams were prepared by using supercritical CO 2 . The introduction of PBS improves the mechanical and crystallization properties. In the foaming process, PBS causes the deterioration of melt strength , promotes the cell nucleation, and decreases the cell wall thickness, facilitating the formation of open-cell structure. Owing to the synergistic effect of the increased open-cell content and the improvement of stiffness, 80/20 blend of PBAT and PBS exhibited the highest expansion ratio of 18.4 without shrinkage. PBS plays multiple essential roles in the foaming and shrinking process with CO 2 green blowing agent, providing a widely applicable anti-shrinkage strategy, which also affords shed light upon the large-scale preparation of the biodegradable polyester foams.