A novel selective separation method for cinnamaldehyde and benzaldehyde has been developed using insoluble beta-cyclodextrin polymer as a host and cinnamaldehyde and benzaldehyde as model guests. The insoluble beta-cyclodextrin polymer could form inclusion complex with cinnamaldehyde and benzaldehyde in solid state, so as to selectively separate benzaldehyde and cinnamaldehyde. The inclusion equilibrium constants for cinnamaldehyde and benzaldehyde over the beta-cyclodextrin polymer have been calculated through their solid UV-vis spectra, and the binding energies between beta-cyclodextrin polymer and the two substrates complexes have been calculated with ONIOM2(B3LYP/6-31G(d):PM3) and semi-continuum solvation model. The driving force of the separation between cinnamaldehyde and benzaldehyde is through the different weak interaction with beta-cyclodextrin polymer, i.e., hydrogen bond interaction, which is evidenced by the different binding energies and different inclusion equilibrium constants. (C) 2011 Elsevier B.V. All rights reserved.