The present invention relates to bicyclic tetrahydrofuran lactone derivatives of Formula (1) and a preparation method thereof, and particularly it relates to a process of preparing compounds of Formula (1) by performing an intramolecular cyclization of tetrahydrofuran-allenic acid derivatives in the presence of a phenyl halide, a palladium catalyst and a base: wherein n is 1 or 2, and R is phenyl optionally substituted with C1-C6 alkyl, C1-C6 alkoxy, hydroxyl or C1-C6 hydroxyalkyl group.