<p>This study investigates the vibration characteristics of bolted-flange-joined conical-cylindrical shells (BFJCCSs) through both theoretical analysis and experimental testing. The proposed model incorporates the pressure distribution within the bolted joint and accounts for the flange effect. The energy expressions for the conical and cylindrical shells are derived from Donnell’s shell theory, while those for the flanges are obtained from the Euler-Bernoulli beam theory. The Lagrange equation is used to derive the dynamic equation, and the experimental studies on the BFJCCS are conducted to validate the accuracy of the model. Subsequently, the comprehensive effects of bolt loosening and bolt number on the frequency parameters are analyzed. Additionally, the effects of the flange dimensions and cone angle on the vibration behavior of the BFJCCS are discussed. In particular, the dynamic differences between the welded conical-cylindrical shell (WCCS) and BFJCCS are investigated. It is found that compared with the WCCS, the fundamental frequency of the BFJCCS is reduced by 7.6%, and the corresponding modal damping ratio is reduced by 21.0%. However, the high-order frequencies of the BFJCCS are higher than those of the WCCS, accompanied by a higher modal damping ratio. Compared with the bolt loosening degree, the bolt number has a more significant effect on frequencies. As the bolt number decreases, the impact of the bolt loosening degree diminishes gradually.</p>