Abstract: With the continuous development of underwater acoustic electronic warfare technology, the demand for receiving-while-sending technology of acoustic decoy is increasing day by day. One of the difficulties in realizing this technology is how to increase the isolation between the transmitting end and the receiving end in the acoustic decoy. Due to the absorption of acoustic energy by polymer sound-absorbing material, the sound isolation in acoustic decoy can be improved by laying sound-absorbing material at the receiving end. The finite element software is used to simulate the isolation degree for the simplified acoustic decoy model. The effect of different thickness of sound-absorbing material on the isolation degree is calculated. The result shows that the isolation degree between the transmitting end and the receiving end can be improved by laying sound-absorbing material at the receiving end. And the effect on the isolation degree is almost unchanged when the sound-absorbing material reaches a certain thickness.