The multifunctional antipollution agent is a kind of flushing fluid material made of organically modified bentonite, which can be used to prepare salt water and magnesium based flushing fluid system. This flushing fluid material was successfully applied in a mine of Laos, which indicates that it has strong salt tolerance and antipollution ability, strong inhibition of shale hydration decomposition, effective wall and core protection, especially is suitable for the use in the formations containing the soluble salts of halite (rock salt), sylvite and carnallite.