First , 2 - methyl isocaproy l chloride was prepared by 2 - methylvaleric acid and thionyl chloride. Second, 2 - methyl - 1 - pheny l - 1 - pentanone was synthesized with benzene and isocaproy l chloride in the presence of anhydrous aluminum chloride as a catalyst. The n, 2 - methy l - 2 - hydroxy - 1 - pheny l - 1 - pentanone was prepared by chlorination and hydrolysis with 2 - methyl - 1 - pheny l - 1 - pentanone in the presence of NaOH and CCl4 as chlorinating agent and tetrabutyl ammonium bromide as the phase transfer catalyst. The result shows :w hen n(2 - methylvaleric acid)/n(thionyl chloride) is 1. 0 ∶1. 5, dropwise temperture and time of thionyl chloride is 40 ℃ and 1. 5 h respectively , reaction time is 2. 5 h, anhydrous aluminum chloride is 18. 5 g , benzene is 45 mL, dropwise time of isocaproyl chloride is 0. 5 h , the yield of 2 - methy l - 1 - pheny l - 1 -pentanone is 92. 7 %;when n(2 - methy l - 1 - pheny l - 1 - pentanone)/n(CCl4) is 1. 0 ∶1. 8 , tetrabutyl ammonium bromide is 6 g , mass fraction of sodium hydroxide is 20 % and reaction time is 5 h , the yield of 2 - methyl - 2 -hydroxy - 1 - pheny l - 1- pentanone can be up to 91%. The structure of the product was characterized by elemental analysis, IR and MS.