Effective conductivity of SOFC electrodes is an important parameter for predicting the ohmic loss in SOFC. This work investigates the effective conductivity of SOFC electrodes via numerical simulation. The microstructures of porous electrodes are reconstructed numerically by packing spherical particles in a computational domain, followed by a dilation process to simulate the sintering procedure. The effects of various parameters on the effective conductivity of the electrodes are investigated, including material composition, porosity, particle size and contact angle. The results are useful for understanding the microstructure properties of SOFC composite electrodes and for subsequent electrode optimization.