Abstract: A 3D model of Bottlenose dolphin is constructed based on the COMSOL Multiphysics platform. The scattering directional characteristics of dolphin in transceiver testing system are calculated by finite element method under the irradiation of the LFM signal of 1 kHz to 5 kHz. The results show that:（1） The probability distribution of omni-directional target strength（TS） of the dolphin model from 0 ° to 360 ° can be known, and the TS values are mainly distributed in the range of-36.4 dB to-11.2 dB;（2） The frequency response of the lung model is similar to that of the dolphin model. The lung is the main contribution of the total acoustic scattering of the dolphin.（3） The frequency response of dolphin is shown around 1.2 kHz, 1.9 kHz, 2.9 kHz, 3.7 kHz, with relatively narrow resonance mode valley values at 4.3 kHz, 4.8 kHz, which verifies the existence of Whispering Gallery waves in biological tissue media.（4） The TS distribution of the dolphin also presents a "butterfly" shape at 5 kHz, the TS values are-22.3 dB in the abeam direction,-34.2 dB in the head direction, and-34.3 dB in the tail direction.（5） The accuracy of the numerical calculation is verified by the echo test experiment of the small scaled dolphin model in pool.