Abstract: The accelerating erosion cell designed is described. The mechanism of metal attack in different coal-water slurry (CWS) velocities is proposed. When CWS velocity is below 3m/s corrosion is the dominant attack mode, while over 3m/s, erosion plays a domi-nant role. The corrosion inhibition mechanism of tungstate is explained in two aspects of action pattern and action region. Tungstate ion reacts with Fe~(2+)(Fe~(3+) to form insoluble FeWO_4 on the metal surface (as Fe_2(WO_4)_3 on the outer interface). FeWO_4 fills the pores and defects of oxide on the metal surface. An uniform three-dimensional (3-D) layer is formed.