<p>Rotating cylindrical shells are widely used in numerous engineering fields, and their rotational stability is crucial. In practical engineering, slight changes in structural dimensions and boundary conditions can greatly affect their mechanical performance and influence their rotational stability. This paper establishes the dynamic equations of rotating cylindrical shells through the Assumed mode method and the extended shape function method. Artificial springs are introduced to simulate different boundary conditions. The mode localization phenomenon of cylindrical shells under different forms of axial non-uniform faults and changes in boundary conditions is analyzed and verified by simulation and experiment. This study focuses on investigating the effects of boundary conditions and typical axial non-uniform configurations on the rotational stability of rotating cylindrical shells, and summarizes the influence of mass distribution on critical speeds. The evolution process of mode localization with rotational speed are systematically examined. The research findings are expected to provide valuable references for the optimal design and safety assessment of rotating shell structures.</p>