The effects of anode porosity on thermal stress and failure probability of a planar solid oxide fuel cell (SOFC) are investigated by finite element method (FEM). The thermal stress and failure probability in planar SOFC with and without considering porosity (CP) were compared. The results show that the compressive stresses are generated in the electrolyte layer, while tensile stresses are generated in Ag-CuO and BNi2 layer because of the compatibility of deformation. In the case of considering anode porosity, the compressive stresses in anode and electrolyte layer and the tensile stresses in cathode layer are all decreased. Comparing to without CP, the thermal stress with CP in electrolyte and cathode layer decreases by 33.2% and 46.9%, respectively. The anode layer has a large risk of failure (5.6489 x 10(-4)) than that of cathode and electrolyte layer at as-fabricated state. And the failure probability at cathode layer at start-up reaches 0.998. The failure probability decreases gradually in the period of creep. The failure probability in anode, cathode and electrolyte layer with CP all decrease comparing to without CP. The porosity of anode could lead to the decrease of tensile thermal stress, resulting in the decrease of failure probability in cathode layer. The reduction speed of failure probability at creep stage with CP is bigger than that without CP. As the increase of porosity, the failure probability decreases due to the decrease of the tensile stress. Copyright (C) 2016, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.