This contribution aims at the mechanism of electrochemical mechanical finishing (ECMF). The change in surface micro-profile of workpiece and its influence on anodic electrochemical dissolution (ECD) as well as the action of the mechanical role were investigated. The results show that the peak-like micro-profile of surface is in favor of improving the ability of ECD. The mechanical role not only scratches the passive film resulted from ECD, but also changes the surface micro-profile of the workpiece. The action of the mechanical role influences the final finished surface quality of the workpiece.