Abstract: Due to unobservable operating environment, gas-liquid mixing state of self-excited deduster can not be observed in real time, so it is difficult to avoid dust escape caused by fluctuation of liquid surface and intermittent excitation of traps in gas fluid coupling process, and determining of operating parameters (liquid level, wind speed, etc) of the deduster lacks of scientific basis, so it is difficult to guarantee removal efficiency of the deduster. In order to solve the above problems, an on-line monitoring system for self-excited deduster was designed. The system uses five characteristics parameters as the important identification basis of flow pattern to identify the gas-liquid flow pattern inside the deduster quantitatively, including resistance parameter, liquid level parameter, power spectral density value, relative power spectral density value and frequency characteristic segment of pressure signal. The system can adjust operating parameters of the deduster, and realizes on-line monitoring of gas-liquid mixing state in the self-excited deduster.Test results show that the system can realize real-time and precise recognition for gas-liquid flow pattern of deduster with 95.6% recognition rate.