The expanded polypropylene beads made by ethylene-propylene-butene-1 ternary copolymer (TPP) were prepared by an autoclave-based batch foaming process using non-supercritical CO2 as the foaming agent. Herein, smaller polypropylene micropellets (~0.6 mm) were obtained from three kinds of polypropylene with different comonomer content by underwater micro-pelletizer system. Addition of CO2 in the PP melt on the melting temperature led to the noticeable plasticization of CO2. Effects of addition of comonomer on the foaming processing and cell structure of EPP beads are investigated preliminarily. The results from differential scanning calorimetry indicated that the double melting peaks of beads moved to higher temperature with increasing saturation temperature and pressure. The innovative application of EPP profile is introduced.