The invention discloses a preparation method of 3,4-cyclopentyl-1-tetralone; under a condition of the presence of a copper catalyst, a nitrogen ligand, a reducing agent and an alkali, alkenyl benzaldehyde and an alpha-brominated unsaturated carbonyl compound are stirred in a solvent and subjected to a reaction for 12 hours at room temperature, and the 3,4-cyclopentyl-1-tetralone is obtained after postprocessing. The method is simple to operate, mild in condition, good in functional group compatibility, wide in substrate applicability, high in yield and good in selectivity, and only needs one-step operation.