Abstract: A new wet FGD process in which SO₂ was absorbed in the bubble reactor using granular limestone and acetic acid was proposed. The main difference as compared with the conventional wet FGD process was to utilize granular limestone directly as desulphurization reagent with simultaneous addition of acetic acid. Thus, the pulverization of limestone, which causes power consumption, could be saved. By using granular limestone（165—200 μm） directly as absorbent only without acetic acid, SO₂ removal efficiency and limestone utilization were too low,60.7% and 44% respectively.By adding 10—30 mmol•L^-1 acetic acid,desulphurization was increased to 95% and limestone utilization was enhanced to 93.5%.The desulphurization efficiency and limestone utilization of using fine limestone were 88% and 92.9% respectively under the same operating conditions.The buffer capacity of system was also enhanced by adding organic acid. With concentrations of 5 and 10 mmol•L^-1 acetic acid, it took 45 min for the pH value to drop from 6.0 to 4.0.Furthermore, with increasing organic acid concentration the effect of buffer action was more obvious. It could better adapt to the fluctuation of SO₂ concentration of flue gas,make operation more flexible, and improve process reliability. The mechanism of promoting SO₂ absorption by acetic acid was suggested.