The invention discloses a method for preparing 1,2,3,4-tetrachloro-hexafluoro butane. In the presence of an oxygen-containing organic compound catalyst, 1-iodine-1,2,2-trifluoro-1,2-dichloroethane and zinc particles react to prepare 1,2,3,4-tetrachloro-hexafluoro butane, wherein the oxygen-containing organic compound catalyst is one or a combination of more of alcohol, ketone, ester, ether and amide; the added quantity of the oxygen-containing organic compound catalyst accounts for 5 to 50 weight percent of that of the 1-iodine-1,2,2-trifluoro-1,2-dichloroethane; the particle size of the zinc particles is of between 3 and 6 mm; and the added quantity of the zinc particles accounts for 10 to 50 weight percent of that of the 1-iodine-1,2,2-trifluoro-1,2-dichloroethane. The invention also provides a method for preparing hexachlorobutadiene from the 1,2,3,4-tetrachloro-hexafluoro butane. The hexachlorobutadiene can be used as a polymer monomer, an etching gas or the like.