The preparation method is to add metered methyl epentinic acid, solvent, and trifluorotrichloroethane into the reaction kettle in turn, start stirring, and add a catalyst to heat until the reaction is complete for about 10 hours, after the solvent is recovered, the water is washed, and the oil layer is separated, and the oil layer is distilled to obtain 4,6, 6-trichloro-7, 7, 7-tri, then, at low temperature, slowly drop and add the pre-prepared sodium tert-butanol solution, and continue the reaction until the reaction is complete for about 3 hours. After the tert-butanol is recovered, a quantitative solvent is added to dilute and washed with water. After the solvent is recovered, the oil layer is distilled to obtain a colorless or light yellow transparent liquid, which is cis-trans 3-(2-chloro -3, methyl 2-dimethylcyclopropane carboxylate.