Solid oxide fuel cells (SOFCs) have begun to attract attention because of their low emissions, high-energy conversion efficiencies, and flexibility with various fuels. However, it is very difficult to produce large area unit cells with a high degree of flatness using tape-casting and co-firing. Therefore, the understanding of unit cell behavior during co-firing is very important in the manufacturing field of SOFCs. The densification-based finite element method (DFEM) was selected for modeling and analysis of the co-firing behavior of a SOFC unit cell. The DFEM corroborated the experimental results. The anode support thickness mainly affected the camber among the SOFC components. When applying compressive force during co-firing, the camber was minimized when the loading density was near 12 g cm −2, and the deformation rate increased rapidly as the compressive loading density increased. Additionally, the application of the compressive force affected the internal stress distribution. The co-fired cell with an applied optimal compressive force showed homogeneous stress distribution.