a-/b-axis-oriented epitaxial bismuth layer-structured ferroelectric thin films were epitaxially grown on (101)-oriented oxide with rutile structure. The long-range lattice matching between the ferroelectric layer and the bottom rutile layer, particularly the number of rutile units facing one ferroelectric unit and the surface orientation, were discussed for (100)(010)Bi4Ti3O12//(101)TiO2 structure. Cross sectional transmission electron microscope analysis suggests that seven rutile units lie under one a-/b-axis-oriented Bi4Ti3O12 unit with lower misfit dislocation density comparing to eight rutile units by one Bi4Ti3O12 model. Based on this result, the surface orientation at the interface was simulated to give us an appropriate ion alignment model. The titanium layer in the (101)TiO2 structure is most likely to match with the oxygen layer in the a-/b-axis-oriented Bi4Ti3O12 film.