In the additive and subtractive integrated manufacturing process of complex thin-walled parts, the material removal of thin-walled parts changes the structural modal parameters, and the modal changes are often ignored in conventional dynamic response analysis, which results in the deviation of vibration deformation predicted under the action of periodic milling forces. Therefore, based on the matrix perturbation theory, the influence law of material removal on modal parameters of thin-walled parts is analyzed, the machining process modal parameters of thin-walled parts are obtained and compared with the simulation results of commercial finite element software, and the accurate calculation of modal parameters of thin-walled parts in material removal process is realized, which provides theoretical basis for vibration deformation analysis of thin-walled parts processing.