A trichloro ethylene preparation method relates to chlorinated alkene. The method comprises the following steps: 1), mixing vaporized tetrachloroethane with acetylene to form a raw material mixture gas, and controlling the molar ratio of tetrachloroethane to acetylene at 1:(0.5-2); 2), pumping the raw material mixture gas into a reactor filled with a catalyst for reaction at controlled temperature, pressure and gas flow rate, so as to allow the conversion rate of acetylene or tetrachloroethane to reach more than 70 percent; and 3), cooling the reaction product obtained in the step 2 to a room temperature by water, and separating out liquid-phase product and gas-phase product, wherein the liquid-phase product passes through a rectification column to produce a trichloro ethylene product, the gas-phase product, which is subjected to compression and freezing, is adopted for further liquification separation of vinyl chloride, and the uncooled gas after the completion of compression and freezing is used for circulating and recycling. According to the method provided by the invention, tetrachloroethane is adopted to eliminate coupling between the reaction and an acetylene addition reaction so as to form intermolecular energy direct conversion; and accordingly, the energy transfer process is simplified, the reaction energy consumption is reduced, the technological process is also simplified, and the equipment investment is lower. In addition, as for by-products, vinyl chloride is higher than hydrochloric acid in additional value.