The present invention provides a method of operating a powder coating system, comprising at least one coating device, a coating compartment and a suction system in the coating compartment. In the method, a workpiece is passed through a coating compartment. The coating powder is discharged by the coating device to the workpiece and excess coating powder is sucked off from the coating compartment, wherein the powder mass flow of the coating powder discharged by the or each coating device is detected and the suction system is controlled in accordance with the powder mass flow. For this purpose the invention provides a powder coating system comprising a measuring means for detecting the powder mass flow of the coating powder discharged by the or any coating device, and an actuator means for setting the suction system in accordance with the powder mass flow.