Abstract: The sound and vibration transmission characteristics between double cylindrical shells in different flow fields were studied with the analytical method.The Flügge equation of thin shell was applied to describe the shell vibration.By this equation,stiffening member was usually regarded as equivalent supporting force to the double cylindrical shell,and then the solution of coupled equation of sound-flu-id-structure interaction was obtained.The calculated results were presented in terms of surface vibration mean-square velocity stage,radiation sound power and radiation efficiency.In the numerical analysis,the influences of connection variation b etween finite-length double cylindrical shells and varied flow fields of outside on the acoustic radiation performances were analyzed.The results show that in the event of the vibration noise excited by inner shell in the low or medium frequency range,the radiated noise of transmission path into the flow field of outside is mainly via the solid plates connected inner and outer shells other than the fluid medium in the annular flow f ield.