The invention provides fume purification equipment comprising a sulfur dioxide absorbing device, a first buffering device and a sulfur dioxide desorbing device, wherein the sulfur dioxide absorbing device is filled with a sulfur dioxide absorbent and is provided with an absorbing device feeding hole and an absorbing device discharging hole; the first buffering device is provided with a holding tank for holding absorbent having absorbed sulfur dioxide and is provided with a first buffering device feeding hole and a first buffering device discharging hole, and the first buffering device feedinghole is in liquid connection with the absorbing device discharging hole and is used for receiving the absorbent having absorbed sulfur dioxide from the absorbing device; the sulfur dioxide desorbing device is provided with a desorbing device feeding hole and a desorbing device sulfur dioxide discharging hole, the desorbing device feeding hole is in liquid connection with the first buffering device discharging hole and used for receiving the absorbent having absorbed sulfur dioxide from the first buffering device, and the desorbing device is further provided with a heating device for releasingsulfur dioxide by raising the temperature. The fume purification equipment provided by the invention can enrich and recycle sulfur dioxide from fume. The invention also provides a method for preparing sulfur acid from fume.