The invention provides a preparation method of 2-(2', 2'-difluoroethoxyl)-6-trifluoromethyl phenyl propyl sulfide, having the following processes: reacting m-trifluoromethyl phenol with p-toluenesulfonyl chloride, trifluoromethanesulfonic anhydride or 3, 5-dinitrobenzol sulfonyl chloride in a solvent containing organic base or a solvent containing triethylamine hydrochloride and organic base, andthen, collecting a compound having a formula (III) from reaction products, dissolving the compound in butylene oxide, adding tetramethyl ethylene diamine and diisopropylamine, at a temperature range from -25 DEG C to -100 DEG C, adding butyl lithium cyclohexane solution for reaction, and then, adding dipropyldisulfide, and collecting a compound having a formula (II); reacting the compound having the formula (II) with 4-nitrogen, nitrogen-dimethyl pyridine and difluoroethanol for catalytic reaction in the solvent, and then, collecting a compound having a formula (I) from the reaction products.The invention simplifies reaction conditions, optimizes the technology, reduces production cost, and improves synthesis effects. The general formula of the reaction is as follows.