Microtubular solid oxide fuel cells (SOFCs) are shown to be robust under rapid temperature changes and have large electrode area per volume (high volumetric power density). Such features are believed to increase a variety of application. Our study aims to establish a fabrication technique for microtubular SOFC bundles with the volumetric power density of at 0.7 V. So far, we have succeeded to develop a fabrication technology for microtubular SOFC bundles using anode supported tubular SOFCs and cathode matrices with well-controlled microstructures. A key to improve the performance of the microtubular SOFC bundles is to optimize the microstructure of the cathode matrices because it influences a pressure loss for air and electric current collection. In this paper, a simulation study of an air flow, temperature, and potential distributions in the microtubular SOFC bundle was conducted in order to understand the characteristics of the present bundle design. In addition, operating conditions of the microtubular SOFC bundles was discussed for realizing the target power density of .