NOVELTY - Preparing 1-(2-halophenyl)-3-methyl-butanone-1 comprises reacting phosphorus trichloride, 2-halobenzoic acid and N-methoxyl methylamine as a raw material in the presence of anhydrous toluene as solvent, reacting (A) with isobutylmagnesium bromide in the presence of anhydrous tetrahydrofuran as a solvent under a protection of nitrogen, quenching the mixture by saturated sodium bicarbonate (NaHCO3) solution and then extracting by ethyl acetate, drying the extracted product and then filtering, and condensing the filtrate and then purifying by column chromatography    USE - The method is useful for preparing 1-(2-halophenyl)-3-methyl-butanone-1 (claimed).    ADVANTAGE - The method simply and economically provides 1-(2-halophenyl)-3-methyl-butanone-1 with high efficiency and yield (more than 80%) and product quality (more than 99%) in an eco-friendly manner.    DETAILED DESCRIPTION - Preparing 1-(2-halophenyl)-3-methyl-butanone-1 comprises (1) reacting phosphorus trichloride, 2-halobenzoic acid and N-methoxyl methylamine as a raw material in the presence of anhydrous toluene as solvent at 0-65 degrees C for 2 hours, where the mole ratio of phosphorus trichloride, 2-benzoic acid and N-methoxyl methylamine is 1:1-1:3, quenching the mixture by saturated sodium bicarbonate (NaHCO3) solution and then extracting by ethyl acetate, drying the extracted product and then filtering, and condensing the filtrate and then purifying by column chromatography to obtain 2-halo-N-methoxyl- N-methylbenzamide (A), and (2) reacting (A) with isobutylmagnesium bromide in the presence of anhydrous tetrahydrofuran as a solvent under a protection of nitrogen at 25-65 degrees C for 2-6 hours, where the mole ratio of (A), isobutylmagnesium bromide to anhydrous tetrahydrofuran is 1:4-1:8, quenching the mixture by saturated NaHCO3 solution and then extracting by ethyl acetate, drying the extracted product and then filtering, and condensing the filtrate and then purifying by column chromatography.