To get a wide-band transducer, the piezoelectric sandwiched transducer with a frustum hole in its head piece is presented in this paper. The equivalent circuit is derived, and the expressions of the equivalent mass and the equivalent impedance of the transducer are obtained by using one-dimensional (1D) design theory. Moreover, the expressions of the mechanical quality factor and the frequency bandwidth are obtained and the transmitting voltage response of the transducer is calculated by using finite element method. The theoretical results show that the frequency bandwidth of the transducer with a hole is wider than that without a hole when their resonant frequencies are almost equal. The tested results are in good agreement with the theoretical calculations.