Abstract: Heavy medium coal separation is a dynamically variable process. The adjustment and control of medium level in tank and medium suspension density play a crucial role in the process. The stability of the abovementioned 2 factors have a great bearing on the medium consumption, product quality and separation efficiency. Whenever the liquid level in a dilute medium tank (all buffer tanks excepting qualified medium tanks) varys abnormally, adjustment needs to be made of the inlet of medium, circulating water and the medium-water mixture directly from separation system. As for the qualified medium tank, if any abnormal change of liquid level or suspension density occurs, the principle of making the corresponding adjustment required first for the primary washing process and then the secondary washing process and adjusting first suspension density and then liquid level needs to be followed.