The invention discloses 1-phenyl-1-(p-tert-butyl methylphenyl)ethane and a synthesis method thereof. The synthesis method comprises the following steps: 1) with styrene and p-tert-butyl toluene as raw materials and under the effect of a solid acid catalyst, performing an alkylation reaction, wherein the reaction formula is shown in the specification; and 2) after the reaction, separating the solid acid catalyst; performing further adsorption, neutralization and decoloration filtration using a solid material consisting of activated clay and magnesium oxide in a mass ratio of 10:1; performing reduced-pressure distillation through a water pump to recycle excess p-tert-butyl toluene; and performing reduced-pressure distillation through a vacuum pump to obtain 1-phenyl-1-(p-tert-butyl methylphenyl)ethane. In the invention, the adopted catalyst can be recycled to avoid environmental pollution; and meanwhile, the use of volatile, toxic and hard-to-treat catalysts such as sulfuric acid and aluminum trichloride is avoided. The preparation technology has the characteristics of mildness and controllability, few byproducts and high yield.