Abstract: In order to guarantee the safe and stable operation of concentrated hydrocyclone, classifying and thickening experiments of total iron mine tailings are studied in this paper. Experimental results indicate that feed concentration has little influence on concentration effect; feed pressure has positive relation to the concentration effect. According to the results, an automatic control method of concentrated hydrocyclone is presented. To autocontrol the feed flow rate and feed pressure of the hydrocyclone, Programmable Logic Controller (PLC) is used as followed: three closed-loop feedbacks of liquid level are carried out to control the level of the feed pump pool, and two PID control outputs are implemented to regulate frequency of the converter.PC monitor. Meanwhile, configuration software are applied to have functions of real time monitoring as well, automatic start-stop, man-machine conversation and system alarm. Combined use of PLC and configuration software realizes automatic control and guarantees safe and stable operation of concentrated hydrocyclone.