The invention discloses a method for continuously synthesizing 2,3,3,3-tetrafluoropropene in a gas phase. In the presence of a catalyst, tetrachloroethylene and methyl chloride undergo a telomerization reaction to generate 1,1,1,2, Catalyzed fluorination of 2‑pentachloropropane and 2,3,3,3‑tetrachloropropene, ,1,1,2,2‑pentachloropropane and 2,3,3,3‑tetrachloropropene to 1,1 ,1,2,2-Pentafluoropropane and 2-Chloro-1,1,1,2-Tetrafluoropropane, 1,1,1,2,2-Pentafluoropropane and 2-Chloro-1,1,1 ,2-Tetrafluoropropane Catalytic Dehydrohalogenation to Prepare 2,3,3,3-Tetrafluoropropene. The invention adopts a continuous method for reaction, the raw materials are economical and easy to obtain, and the reactions of each step are carried out in a reactor, the reaction conditions are easy to control, and the equipment operation is simple; and the conversion rate of each step of the preparation method is better, and the yield of the target product is higher , low equipment investment cost and other advantages, has a wide range of industrial application prospects.