Bagasse and starch were used as the main raw materials to manufacture biodegradable cushiony package material by microwave foaming. The result indicated that the content of glycerol, NH4HCO3, water, foaming time, foaming temperature, PVA and starch can all impact the performance of product. When setting foaming time as 90 s，foaming temperature 100℃ and ration of bagasse:water:PVA:starch:glycerol:NH4HCO3 as 1:7.5:0.375:1:0.75:0.5, the performance of product is optimal, the stress-strain curve of the product presents a straight line and the product can be considered a linear elastic material.