AbstractThis paper, based on the boundary‐element technique, presents a perturbation method which can be applied to reanalysis of the eigenvalues and eigenvectors in an elastic structure. Regarding the shape changes of a structure as the perturbation of its surface nodes within the neighbourhood of the given values, this method uses the perturbation formula to obtain the eigensolutions of the modified system without solving the generalized eigenvalue problem. Finally, the authors give some sample examples to demonstrate the validity of the metho