This paper deliberately analyzes the stress distribution of rotor plate with mounting holes. A FEM-based computational model is established by utilizing ANSYS. The depth, diameter and gyration radius of the mounting holes are selected as main effective factors while extreme stress and deformation of rotor plate as main evaluation index. Combining with the orthogonal experimental method to analyze the parameters' impacts on the evaluation index, this paper has obtained corresponding numerical calculation formula. Furthermore, it concludes a complete calculation methodology for mechanical property of irregular rotor plate with mounting holes, thus provides the basis for design of high speed rotary system. The methodology has prevalent value for practical applications.