Sinopec Dalian Research Institute of Petroleum and Petrochemicals developed the "low temperature diesel absorption" VOCs treatment device for an aromatics and styrene tank farm. However, the waste gas volume sucked into the liquid ring compressor is always unstable. In this paper, a new automatic bleed gas volume control scheme of liquid ring compressor was adopted, the optimal control parameters were obtained by designing the bleed air control scheme for the compressor motor frequency and the opening of the return valve of the liquid ring compressor according to the pressure on the pipeline connected to the tank area. The results show that this technology can meet the requirements of energy saving and consumption reduction while ensuring that the exhaust gas is discharged up to the standard, and take into account the long?term stable operation of the equipment.