Gradient particle size anode has shown great potential in improving the electrical performance of anode-supported solid oxide fuel cells (SOFCs). In the present study, a 3-D comprehensive model is established to study the effect of various gradient particle size distribution on the cell electrical performance for the anode microstructure optimization. The effect of homogeneous particle size on the cell performance is studied first. The maximum current density of homogeneous anode SOFC is obtained for the comparison with the electrical performance of gradient anode SOFC. Then the effect of various gradient particle size distribution on the cell molar fraction and polarization losses distribution is analyzed and discussed in detail. Increasing the particle diameter gradient can effectively reduce the anodic concentration overpotential. Decreasing the particle diameter of AFL2 is beneficial to reducing the activation and ohmic overpotentials. On these bases, the comprehensive electrical performances of SOFCs with gradient particle size anode and homogeneous anode are compared to highlight the optimal gradient particle diameter distribution. In the studied cases of the present work, the gradient particle diameter of 0.7 μm, 0.4 μm and 0.1 μm at ASL, AFL1 and AFL2 (Case 3) is the optimal particle size distribution.