Chromium(Cr) poisoning of the traditional LSM cathode is one of the most critical issues that accounts for instability of solid oxide fuel cells (SOFCs). The poisoning course will introduce alien species in the cathode active regions and it causes phase change and structure deformation, reducing the sites for electrochemical reactions. A 3D model is thus developed by coupling the computational fluid dynamics (CFD) approach with the finite element method to unravel the involved electrochemical processes in chromium poisoning of SOFCs. A function is proposed based on the experimental results to describe the distribution of Cr-related compounds in cathode. The results indicate that chromium poisoning can induce a dramatic decrease in the electric current density, which can also lead to increase of activation polarizations and lower the temperature. Three kinds of thermal stresses are strongly affected by the invasion of chromium into cathodes, which are all significantly reduced with the poisoning extent. The resulting conclusions are beneficial to deeply understand the Cr poisoning of SOFCs and also to material design to prevent cathodes from Cr-based interconnect attack. (C) 2018 The Electrochemical Society.