Abstract: Acoustic scattering from the rings between two shells insonified by an incident plane wave is specially studied in order to deeply understand the mechanism of the scattering from double cylindrical shells with internal ring-stiffened. Only considering the rigid scattering the analytic solutions of the scattering field of the single ring are derived by applying the Kirchhoff approximation.The method is also used to estimate the scattering from the periodic rings. The approximate solutions of the scattering field of the external ring-stiffened finite cylindrical shell are derived with combination of the rigid scattering from the cylindrical shell and the scattering from the periodic rings.The target strength of the model is also calculated using the GRACO method.The theoretical and experimental results show that the rigid scattering plays a major role in the backscattering field.Bragg scattering caused by the periodic rings has important contribution to the scattering field.It also shows that the shielding effect plays quite a big part in the actual situation.