Abstract: With the development of signal processing in underwater acoustics,the demand for broadband signal is arising increasingly.The broadband transducer is the basis of making use of broadband signal.Matching layer technology is the most effective method to broaden the frequency bandwidth of thickness-vibrating transducers.Study is introduced on how to design thickness-vibrating transducers with multiple matching layers.The equivalent circuit model is built on the basis of complex coefficients.The relation of matching layers parameters and transducers response is simulated.It is pointed out that there are some limits to broaden the bandwidth of transducers with single or double matching layers,and the proper thickness of matching layer is not exactly the quarter of wavelength.Samples of thickness-vibrating transducers with single and double matching layers are developed to validate the simulation results.The tested results are in good agreement with the simulation results.