Abstract: To investigate the coupling sound radiation characteristics of 3 side-by-side flexible cylindrical shells, a mathematical physical model is established which involves the sound radiation and scattering of every cylindrical shell. In this model, Mode-Expansion method is adopted to solve the coupling equations, Hankel Function Transferring is used to describe the coupling of vibration and sound of 3 shells. Then, the effect of multi-rescattering of the shells is verified, and the difference between the sound field distribution of 3 combined cylindrical shells and the single shell is studied, and also the sound pressure level and the sound power level. The results show that the elastic interaction of the shells affects not only the low-frequency but also the high-frequency sound field; and the existence of the lateral shells can lead to the sound-shielding in the abeam direction, yet the sound enhancing of the vertical direction.