Tungsten is a promising material for the mold of glass components owing to its excellent mechanical and chemical properties. Electrochemical polishing (ECP) has been proposed for the damage-free and highly efficient surface finishing of tungsten. In the paper, a comprehensive study of the anodic behaviors of tungsten during ECP under different applied potentials has been carried out. A mirror surface with a Sa roughness of 3.73 nm has been obtained by ECP for 10 mins demonstrating its effectiveness. The changes of surface morphology, roughness and electric current under different potentials have been experimentally investigated and analyzed. On the basis of the changes of surface morphology and current density, ECP of tungsten was divided into 3 stages including the etching stage in which rough etching marks were formed by crystallographic etching, the brightening stage in which ultra-smooth surfaces with clear boundaries were obtained and the pitting stage in which crystallographic pitting occurred. The probable material removal mechanisms of these 3 ECP stages were proposed and experimentally validated. The presented findings are of great value for understanding and process development of ECP of tungsten.