Abstract: The newest research progress of starch-based and lignin-based foams is summarized. The extruded and baked starch-based foams and lignin-based foams as intensifiers in foamed plastics are discussed. The supercritical fluid extrusion (SCFX) process for starch extrusion foaming and its kinetics are introduced. Furthermore, the problems to be resolved in the developments of starch-based and lignin-based foams and their application prospects are presented.