Abstract: In order to realize precise control of automatic flotation reagent addition and obtain optimum separation indices, modeling is made of the reagent dosing variables with the proportion of dirt in raw coal as a disturbance variable, in line with the unique property of the raw coal treated by Xinzhuang Coal Preparation Plant. An introduction is made to the working principle, structure and functions of the automatic reagent dosing control system. Practice shows the use of the system has led to consistency of concentrate quality, increase of yield of flotation concentrate and reduction of labor intensity.