The invention discloses a synthetic method of 1,1,1,4,4,4-hexafluoro-2-butene, and the synthetic method comprises the steps of carrying out a reaction between hexachlorobutadiene and hydrogen fluoride in the presence of a catalyst to generate 1,1,1,4,4,4-hexafluoro-2,3-dichlorobutane, and carrying out a reductive dechlorination reaction on the 1,1,1,4,4,4-hexafluoro-2,3-dichlorobutane in a solvent by using zinc powder to generate the 1,1,1,4,4,4-hexafluoro-2-butene. According to the synthetic method, the process is simple, the steps are short, the reaction conditions are mild and the product can be obtained through two steps of reaction; and the raw materials are easy to get, the cost is low, and the byproduct hexachlorobutadiene obtained by reducing tetrachloroethylene by carbon tetrachloride at high temperature can be used as a raw material, so that the cost is further reduced.