The invention provides a synthesis method of 1,1,2-trichloro-3-fluoropropylene, comprising the following step: in the presence of a polyalcohol solvent, carrying out a reaction on 1,1,2,3-tetrachloropropene and an alkali metal fluoride at 90-120 DEG C for 1.0-10h to obtain 1,1,2-trichloro-3-fluoropropylene. The molar ratio of the alkali metal fluoride to 1,1,2,3-tetrachloropropene is (1-5):1, wherein the alkali metal fluoride is sodium fluoride, potassium fluoride or cesium fluoride; and the polyalcohol is glycol, 1,2-propanediol, 1,3-propanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, tetraethylene glycol or glycerol. The synthesis method provided by the invention is mainly applied to preparing 1,1,2-trichloro-3-fluoropropylene.