Abstract: The trouble with the operation of the dense medium separation system of the plant is its inability to operate under stable control and make timely response to control in operation. Through analysis of the operating conditions of the plant,a closed loop control system capable of making real-time regulation of medium density is developed based on result of comparison of two alternative schemes-one is based on clean coal ash and the other,on raw coal ash. The control system is developed with an aim to turning the dense medium separation system into an intelligent one through making it possible to operate in automatic,semi-automatic or manual mode and by adding more functions to the system. Through the transformation,the dense medium separating system can now work under unattended condition with reduced labor intensity,higher consistency of clean coal quality and yield and much improved economical,social and environmental protection result.