The propagation characteristics of the vibration power flow in a submerged cylindrical shell with joint discontinuity are investigated by the wave propagation approach. The motion of the cylindrical shell and the pressure field in fluid are described by the Flügge shell theory and the Helmholtz equation, respectively. And the dynamic equations of the system are obtained by the coupling between the shell and the fluid. Then, an analysis of the vibration power flow transmission and reflection at the joint discontinuity is presented and the power flow transmission ratio Tr through the joint discontinuity is studied. Results show that the joint discontinuity can reduce the mean value of the Tr and thus, reduce the energy level of the transmitted vibration, as it has the effect of partially reflecting some of the incident wave with relations to its physical and geometric parameters. The influences of the fluid and the material damping of the joint discontinuity are also studied.