Abstract: To get a wide-band transducer, the piezoelectric sandwiched transducer with a frustum hole in its fore-metal is presented. First, the equivalent circuit and the resonant frequency equations of this peculiar transducer are derived, and the expression of the equivalent mass and equivalent impedance relative to a inside surface of the transducer are derived by means of one-dimensional design theory. Moreover, the expression of the mechanical quality factor and the band wide are obtained. Meanwhile, the transmitting voltage response of the transducers are calculated by using finite element method. The theoretical calculations and analysis results show that the band of the transducer with hole is wider than the one without hole while their frequency are same for the hole to a certainty size range. The results of measurements have a good agreement with the theory's.