Abstract: Abstract: Extrusion die is the key device in extrusion molding, a reasonable design of the die can ensure the quality and yield of products. A series of sheet dies were designed according to the qualification.The designed dies were utilized to do the foaming experiments, processing parameters were recorded during the experiment, and the foaming products were examined and tested, especially the influence of the die structure on the expansion ratio and foam structure of the polypropylene foams was discussed emphasisly. At last, the experimental results suggested that the height and length of the die channel were the main factors that influence the polypropylene foaming sheet.