Abstract: The cascaded acoustooptic interaction is usually used for the need of the devices'structure and function when the acoustooptic devices are designed and fabricated. The frequency shifting and beam deflection of the Bragg acoustooptic interaction in cascade is analyzed according to general Bragg acoustooptic interaction theory. Different frequency shifting and beam deflection can be obtained when the different cascaded acoustooptic interaction scheme is used. An important conclusion is presented that the doubly and frequency-shifted diffracted light propagates in a fixed direction irrespective of magnitude of frequency shift if the two acoustic wave frequency is changed rationally.