Closed-loop control method of electrostatic precipitator outlet dust concentration was studied to solve the problems of high energy consumption of dry electrostatic precipitator in 1000 MW coal-fired units and the failure to achieve closed-loop control of concentration． Firstly，for dry electrostatic precipitator with a five-field structure，a concentration control method combining feedforward control of the first three-stage electric fields and closed-loop control of the last two-stage electric field was proposed． The IMC-PID parameter setting method was used to set the PID ( Proportional Integral Derivative) controller parameters，and a disturbance observer was added to the PID controller to enhance the anti-disturbance ability of the system． Finally，the method of fuzzy weighted switching was used to achieve smooth switching between the control functions of each load point model． The simulation and experimental results show that the proposed control method can realize the fixed value control of electrostatic precipitator outlet dust concentration and has good performance．