Appropriate mechanical milling in dry ambient can improve the mixing state of two powder materials as well as produce their composite particles. In this study the influences of milling on microstructure and performance of anode supported SOFCs was investigated. First, NiO and YSZ powder mixture was milled using an attrition type apparatus for 5 and 30 min. The SOFCs were made through conventional ceramic processing with the milled powder mixtures. The different milling time brought to significant change in power density of the SOFCs. When the powder mixture milled for 5 min was applied, maximum power density of the cell was 0.44 W·cm-2 at 800 °C. Contrarily, 0.75 W·cm-2 was obtained at the same operation temperature when the powder mixture milled for 30min was applied. Structural analysis revealed that the different power density was strongly related to the different anode microstructure. Prolonged milling resulted in homogeneous porous composite layer with fine Ni and YSZ grains, indicating larger triple phase boundary (TPB). It was demonstrated that the appropriate mechanical milling followed by ceramic processing improves the microstructure, and therefore enhances electrochemical activity of the anode.