IR-visible sum-frequency generation (IV-SFG) vibrational spectroscopy and molecular dynamics (MD) simulation were used to study local layering order at an interface of 1-butanol-d9 and 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF6) room-temperature ionic liquid (RTIL). The presence of local non-polar layer at the interface of two polar liquids was successfully demonstrated. In SFG spectra of 1-butanol-d9, we observed significant reduction and enhancement in the strength of the CD3 symmetric stretching (r+) mode and the antisymmetric stretching (r−) mode peaks, respectively. The results can be well explained by the presence of an oppositely oriented quasi-bilayer structure of butanol molecules, where the bottom layer is strongly bound by hydrogen-bonding with PF6− anion. MD simulations reveal that hydrogen-bonding of butanol with PF6− anion causes the preferential orientation of butanols: the restriction on the rotational distribution of the terminal methyl group along their C3 axis enhances the r− mode. As for [bmim]+ cations, SFG spectra taken within the CH stretch region indicates that the butyl chain of [bmim]+ points away from the bulk RTIL phase to the butanol phase at the interface. Combining the SFG spectroscopy and MD simulation results, we conclude an interfacial model structure of layering, in which the butyl chains of butanol molecules form a non-polar interfacial layer with the butyl chains of [bmim]+ cations at the interface.