Wall cleaning has been used popularly on tokamaks to reduce impurities and fuel recycling. Since 2008, the plasma facing components of EAST have been all of graphite. Due to the special crystal structure of graphite, high outgassing rate and strong absorption of hydrogen gas are induced. The wall cleaning is in particular important for the pre-treatment before the plasma operation of the machine. In this article, we introduce the wall conditioning system on EAST, and study the removal efficiency of device baking and glow discharge cleaning in different working gases and at different operating parameters. The long duration baking and GDC cleaning in EAST notably reduce the wall outgassing, and impurity radiation. After the cleanings, plasma is easily obtained, which is beneficial for the plasma physics experiment.