The invention discloses a synthesis method for allylbenzene triflumizole intermediate 3-(difluoromethyl)-1-metyl-1H-pyrazol-4-carboxylic acid, and belongs to the field of pesticide pharmacy. The synthesis method is characterized in that 3-(difluoromethyl)-1-metyl-1H-pyrazol-4-carboxylic acid is obtained by reacting 3-difluoromethyl-1-methyl-1H-pyrazol and chloro-formate under the action of a catalyst, and a reaction process comprises the following steps: 1) uniformly mixing 3-difluoromethyl-1-methyl-1H-pyrazol, the catalyst and a solvent A, introducing protective gas, controlling pressure to 10-15 barometric pressures, controlling the temperature to 80-110 DEG C, adding chloro-formate, and controlling adding time of chloro-formate to be 40-60 minutes; increasing the reaction temperature to130-150 DEG C after adding is completed, slowly controlling to reduce pressure to 7-9 barometric pressures within 60-90 minutes, and continuously reacting for 40-62 hours; 2) cooling a system, filtering to remove solid, adding filtrate into water with the volume being 6-10 times of that of the filtrate, regulating pH to 2-3 with acid, extracting with a solvent B, washing extracting liquor with water, drying with a drying agent, and concentrating to obtain a product. The synthesis method has the advantages of relatively short steps and relatively low process cost.