The invention discloses a preparation method of vitamin E. Vitamin E is prepared from trimethylhydroquinone and isophytol by condensation, wherein the condensation is performed in the presence of a Bronsted-Lewis ionic liquid catalyst, and structures of the Bronsted-Lewis ionic liquid catalyst are shown as formulae (A), (B) and (C) in the description. The preparation method has the advantages thatequipment is little corroded, little wastewater is produced, the catalyst is recyclable and easy to separate and losses little, the reaction selectivity is good, the yield is high and the like.