The influence of an ultrasonic field on SO2 desorption from sodium alkali desulfurization regeneration Solution was studied in this work. The SO2 desorption experiments were carried out in the presence and absence of ultrasound at 25 kHz. The results showed that the use of ultrasound could enhance the SO2 desorption rate from the sodium alkali desulfurization regeneration solution. By analyzing the composition of regeneration solutions with different pH values, two steps for the desorption process were proposed, both with and without ultrasound conditions, i.e., the first step was the decomposition of sulfurous acid (H2SO3), and the second step was the decomposition of sodium bisulfite (NaHSO3). Furthermore, the use of ultrasound was seen to promote the first step, while it was not seen to have a significant effect on the second step. It was also found that the decomposition of H2SO3 in the first step could be considered as a gas mass transfer process from the liquid phase to the gaseous phase and the overall volumetric mass transfer coefficient, K-L.a, increased on using ultrasound compared to the value in the absence of an ultrasonic field.