Abstract: In order to solve problems of big lag and strong coupling of density and liquid level of heavy medium suspension in heavy medium coal preparation control system, a mathematical model of density and liquid level control system of heavy medium suspension was established and PFC-PID control algorithm of density and liquid level in heavy medium suspension was put forward on the basis of decoupling the system. Closed-loop control method is adopted to control density and liquid level, namely, PID control technology is used to control decoupled system and make the system stable in inner loop, and PFC control technology is used to solve problem of delay in outer loop, inner loop is taken as generalized prediction objects of outer loop. The simulation results show that the control algorithm has characteristics of low overshoot volume, short setting time and small static error and good ability of anti-interference, and has better control effect than traditional PID control technology.