In order to obtain the acoustic characteristics of jellyfish(Aurelia aurita)at different frequencies， the Target Strength(TS)measurement experiment is carried out on the jellyfish with an echosounder in the pool. The results show that for the jellyfish with about 10 cm umbrella diameter and 60° ~ 90° attitude angle，the measured value of the TS is –66 ~ –63 dB at a single frequency(120 kHz)，which is close to the high flux liquid sphere model， and the measured value of the TS is –61 ~ –59 dB at the broadband (90 kHz ~ 170 kHz)condition，which is close to the Mutlu relational model between TS and umbrella diameter. In addition，the reasons for the differences in the measured TS of the jellyfishes with the same umbrella diameter are analyzed. The conclusion of this thesis will provide a reference for nuclear power plants to conduct the detection of cold source disaster-causing organisms in shallow sea with a broadband echosounder.
