A method for preparing diarylethane is disclosed. Alkylation is carried out in a continuous type process at 100-300° C. under a pressure of 1-45 kg/cm2 G in the presence of a solid acid catalyst while a reactant mixture comprising alpha-methylbenzylalcohol and at least one aromatic hydrocarbon at a volume ratio of 1:1-10, is fed at a weight hourly space velocity of 0.1-10 h−1. The alpha-methylbenzylalcohol acts as an ailylating agent. Diarylethane can be prepared at a low cost, but a high production yield by the method.