Abstract: Presents a control plan for density of dense medium suspension,fluid level and pressure of feeding for process control of dense medium coal separation.Described the design of control system based on Freescale MC908Gp32 micro-processer,and the application of 4-20 mA current ring in process parameters measuring and transmitting circuit,the operation practice shows that this system with better in interference-free,stable in operation and obtained the good result in dense medium separation control system.