Abstract: In order to develop new sustained and controlled release formulation,an inclusion compound of β -cyclodextrin with bifenthrin was prepared by means of liquid phase method,and characterized by UV,differential scanning calorimetry analysis (DSC),IR and 1H NMR.UV and DSC proved that the inclusion compound has been produced.The host/guest ratio of inclusion compound between the β -CD and bifenthrin is 1∶ 1 determined by Job’s continuous variation method.The structure of the inclusion compound was characterized with IR and 1H NMR spectrum.The results indicated that the association of the guest molecule with β -CD was favored by Van Der Waals force,hydrophobic interaction and hydrogen bonds,etc.Its proposed that the benzyl rings of bifenthrin enter into the cavity of β -CD through the wider rim,but the other residues of the molecule are not included.