Abstract: A sonic logging broadband impedance matching transformer modular design method and a module are related to sonic logging. The method includes the steps: obtaining component values of a multimodal equivalent circuit of a piezoelectric transducer by fitting actual impedance data of the piezoelectric transducer through a nonlinear regression method; selecting a T-type network structure composed of a matching capacitor and a matching inductor as a piezoelectric transducer impedance matching network structure; and presetting a to-be-matched frequency band and a reflection coefficient, and taking the multimodal equivalent circuit of the transducer as an artificial circuit load to optimize parameters of the piezoelectric transducer impedance matching network structure and a boosting transformer together so as to obtain final optimized parameters of the piezoelectric transducer impedance matching network structure and the transformer.