Abstract: A new flue gas desulphurization (FGD) technology was developed to absorb SO₂ by using citrate solution as absorbing agent, with hollow fiber membrane and ultrasonic enhancement.Ultrasonic treatment and membrane technology were introduced into the process of FGD.Ultrasonic cavitation and its enhancement of the mass transfer process were discussed.By using the self-designed reactor,the effects of ultrasonic treatment on the stability of citrate solution and hollow fiber membrane for FGD were studied.The results showed that under the condition of frequency 20 kHz, citrate concentration 0.5 mol·L^-1 and pH 4.5, the absorption of sulfur dioxide from flue gas in the hollow fiber membrane module could be enhanced by ultrasonic treatment, but the solution could be heated up,which caused inhibition of absorption.In the process of ultrasonic treatment, citrate solution and hollow fiber membrane remained stable.