Abstract: In order to simplify the local buckling analysis of vacuum towers with outside suspensions, a reduced mechanical model is built for the buckling analysis of a thin-walled cylinder under local radial load and external pressure. Pop cans are used as the thin-walled cylinder specimen. Local radial critical loads are measured under different external pressures. The eigenvalue buckling analysis is used to determine the local radial critical load of the specimen,which agrees well with the experimental result. With the orthogonal design method,an empirical formula for the local radial critical load is obtained by the parametric eigenvalue buckling analysis. Verification example indicates that the empirical formula yields slightly conservative results, which may be used for the local buckling analysis of vacuum tower with outside suspensions.