The invention relates to a method for quickly purging a debenzolization tower before an operator enters the debenzolization tower for maintenance in a coking plant. When the debenzolization tower is maintained, the temperature of steam entering the tower is raised to about 300DEG C, superheated steam distillation-water washing operation is repeatedly carried out for about three times and 51 hours to reduce the concentration of harmful gases in the tower to be lower than national occupational health standards and reach the person entry fire operation standard, and operation risks are reduced. Because the equipment maintenance time is shortened, the operating rate of equipment is improved.