We have actively engaged in the development of Computational Fluid Dynamics (CFD) technology including chemical reaction in Solid Oxide Fuel Cells (SOFCs) and application of this technology to SOFC design. We modified our general purpose CFD program called as TOFAS (TOto Fluid Analysis System) to simulate SOFC phenomena, for example, electrode reaction, reforming reaction and radiation. This report describes the technical information of this modified CFD program and application to several kW-class module structure design. As for TOFAS, Navier-Stokes equation was solved by SIMPLEC and MICCG method in terms of stable and speedy calculation. And this program is wholly parallelized by means of Region Segment Method to calculate large-scale simulation model. We could calculate 3kW-module in 2.5 days, and decide suitable module structure parameter in terms of maximum power generation.