Abstract: The existing heavy medium density control system of Panji Plant suffers the drawbacks of being unable to make real-time ash control, and make timely adjustment of separating density, and it is liable to be affected by artificial factors. To tackle these problems and to cater to the need of bringing the ash of clean coking coal under control, a novel ash monitor is developed in collaboration with an equipment manufacturer according to the characteristics of materials as combustible matter and ash differ in mean atomic number. A heavy-medium separated clean coal ash control system is likewise developed based on fuzzy control theory. It is a double closed-loop control system which can make real-time control of clean coal ash through making real-time correction of the set value with the actually measured data, and making corresponding adjustment of the density with the medium density control system. Practice shows that application of the system makes it possible to realize real-time control of ash of clean coal product of heavy medium separation system, reduce artificial intervention, maintain consistency of product quality increase clean coal yield and enhance automation level.