Porcelain green bodies were prepared using porcelain stoneware tile powder as the major raw material, with silicon carbide (SiC) and CaO as additives. These were fired at 1000–1200°C. The effects of SiC particle size and CaO content on the microstructure and foaming properties of porcelain ceramics were investigated in detail, with a view to further clarify the dominant factors linking foaming behavior to SiC oxidation during firing of a porcelain tile matrix. The results reveal that the size of the SiC particles has a significant influence on the number, size, and interconnectivity of the pores formed in the samples; this effect becomes more pronounced as the SiC particle size is reduced. The addition of a small amount of CaO is shown to significantly accelerate the foaming of a porcelain green body containing SiC, but this effect is gradually inhibited by an increasing formation of anorthite. Finally, the foaming mechanism is also discussed in detail.