The expanded polypropylene beads made by ethylene-propylene-butene-1 ternary copolymer 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. Effects of addition of comonomer on the foaming processing and cell structure of EPP beads are investigated preliminarily (Table 1 and Figure 1). The content of comonomer exerts some influence on the double melting behaviors. The results from differential scanning calorimetry indicated that the double melting peaks of beads moved to higher temperature with increasing saturation temperature and pressure (Figure 2). The relationship between cell morphology and saturation temperature/pressure of expanded polypropylene beads with novel nucleating agent are discussed preliminarily by scanning electron microscope (Figure 3).