Abstract: To increase the control precision of system of inclined lifting wheel separator in Baodian coal preparation plant,utilizing the fuzzy PID control to automatically adjust the density of suspension.Introduced the design of the fuzzy PID control system,and described its composition of hardware and software,working principle,function and features,and analyzed the application effect of the system.The operation practice show that with application of the fuzzy PID control system in refuse discharge workshop in Baodian coal preparation plant,effectively increased the sharpness of separation of clean coal and refuse and lower the medium consumption.