The characteristics of fine particle removal from wet flue gas desulfurization (WFGD) using the simultaneous acoustic agglomeration and supersaturated vapor condensation were investigated experimentally. The impacts of supersaturation degree, residence time and acoustic intensity on the fine particle removal efficiency were demonstrated. High moisture and tiny droplets were contained in the flue gas after WFGD, which benefited the use of coupling external fields in WFGD system. The results showed that the removal of fine particles can be significantly improved in the simultaneous acoustic field and supersaturated vapor condensation. High value of sound pressure level (SPL > 150 dB) was needed to achieve a considerable removal efficiency using acoustic agglomeration only. While low SPL of 130-150 dB can be used to remove fine particle efficiently in WFGD system using simultaneous external fields. Removal efficiency higher than 70% was obtained with S = 1.15 and SPL = 151 dB. The residence time of the simultaneous acoustic agglomeration and condensational growth was determined by the time required by acoustic agglomeration. Particle removal efficiency increased with the residence time, but it tended to be constant as the residence time over 3 s. Multiple horn numbers with low acoustic intensity benefited the improvement of fine particle removal efficiency and the reduction of energy consumption using the simultaneous external fields in WFGD system. (C) 2017 Elsevier B.V. All rights reserved.