The matching layer technology is an important method of improving the performance of transducers. To make the band wider and the sensitivity higher is the researchers′goal.For obtaining the evaluation function to characterize the performance of the transducer, the model of the transducer is established based on the KLM model. By using parameter scanning method, the best parameters of the matching layer are obtained.It′s demonstrated that the thickness of the matching layer influences the transducer more than the impedance,and the attenuation of the matching layer has negative impact on the performance of the transducer. On the basis of the optimization result, a 2.5 MHz transducer is fabricated, whose working media are water and polystyrene.The -6 dB relative bandwidth reaches to 94.3% and 100.8% respectively.