The invention discloses a testing device and a testing method for testing the wave velocity of soil in a centrifuge model by using a piezoelectric element array. The testing device comprises a bent element array structure, a PXI controller, a driving module, a multiplex analog switch and a data acquisition system. The testing method comprises the following steps: sending out an excitation signal in the data acquisition system, executing by the PXI controller, switching a signal channel by the multiplex analog switch, sequentially exciting and receiving in a multiplex way by piezoelectric elements, collecting the excitation signal and received signals, transmitting data to the data acquisition system through an optical fiber slip ring, and performing signal processing and wave velocity discrimination by the data acquisition system. Through the testing device and the testing method, quick testing of the shear wave velocities of multiple pairs of bent elements in the centrifuge model is achieved, and the change of the shear wave velocity of the soil during high-transience catastrophe in a hypergravity centrifuge model test can be monitored; through one excitation, shear wave velocityinformation of the soil at different depths of the model can be obtained at the same time; during the test, signal interference is avoided when an electric signal passes through a slip ring of a centrifuge; the accuracy of the wave velocity discrimination is improved; the testing device is highly integrated and is small in volume and low in cost.