The invention discloses an optimum design method of the dynamic performance of an aero-engine fastening junction surface. The optimum design method comprises the steps of firstly, determining the type, the specification, the assembly technology and the machining precision of adopted bolts; then selecting the aero-engine part fastening junction surface as a design domain, and using a rectangular assembly for description; then adopting several small four-node quadrilateral meshes to divide the design domain, then constructing a rectangular level set function, equalizing the design domain into amaterial model to obtain a unit equivalent rigidity matrix, assembling the equivalent rigidity matrix, and extracting a mass matrix of parts to obtain a kinetic equation and then a target function; then constraining center coordinates of the assembly in the design domain, then conducting iterative optimization, and finally, conducting rounding processing to thus obtain the junction surface joint form with the optimal dynamic performance. By means of the optimum design method of the dynamic performance of the aero-engine fastening junction surface, through optimal design of the junction surface, the optimal solution of the relevant dynamic performance is solved, and a clear design boundary is obtained.