This study focuses on the alkali washing flue gas desulfurization technology and explores its application and existing problems in coal to oil sulfur recovery units.Research has found that alkali washing flue gas desulfurization technology can effectively remove sulfur dioxide from flue gas and improve the efficiency of sulfur recovery devices.However,in practical applications,there are also a series of problems with the alkali washing flue gas desulfurization technology,such as increased system operating pressure,equipment blockage,corrosion,etc.After being put into use,this article proposes corresponding measures and suggestions to solve these problems.