Abstract: For present solid oxide fuel cells (SOFCs), rapid performance degradation is observed in the initial aging process, and the discussion of the degradation mechanism necessitates quantitative analysis. Herein, focused ion beam-scanning electron microscopy was employed to characterize and reconstruct the ceramic microstructures of SOFC anodes. The lattice Boltzmann method (LBM) simulation of multiphysical and electrochemical processes in the reconstructed models was performed. Two samples collected from industrial-size cells were characterized, including a reduced reference cell and a cell with an initial aging process. Statistical parameters of the reconstructed microstructures revealed a significant decrease in the active triple-phase boundary and Ni connectivity in the aged cell compared with the reference cell. The LBM simulation revealed that activity degradation is dominant compared with microstructural degradation during the initial aging process, and the electrochemical reactions spread to the support layer in the aged cell. The microstructural and activity degradations are attributed to Ni migration and coarsening.