Provided is a device and method for avoiding the influence of SO2 desorption on tail gas emissions. The device comprises a drying device, a primary absorption apparatus, a second absorption apparatus and a SO2 desorption apparatus. The drying device comprises a drying tower, a drying circulation pump tank, a drying circulation pump and a drying and acid feeding tube. The primary absorption apparatus comprises a primary absorption tower, a primary absorption circulation pump tank, a primary absorption circulation pump and a primary absorption and acid feeding tube. The second absorption apparatus comprises a second absorption tower, a second absorption circulation pump tank, a second absorption circulation pump and a second absorption and acid feeding tube, and the second absorption and acid feeding tube is connected with a plate heat exchanger. The SO2 desorption apparatus comprises a SO2 desorption tower, an acid supplying tube connected with the primary absorption and acid feeding tube and led to the SO2 desorption tower, an acid return tube connected with the SO2 desorption tower and led to the second absorption circulation pump tank and a bottom air sucking port. The drying and acid feeding tube is connected with the primary absorption and acid feeding tube through a first connecting tube, and the primary absorption and acid feeding tube is connected with the drying circulation pump tank through a second connecting tube. The influence of SO2 desorption on SO2 concentration of tail gas emissions can be effectively avoided.