A program for frequency optimal design of structure composed of bar, beam, plate is developed based on finite analysis system ZR that finite element model, including mesh generation of truss element, beam element and plate element, is automatically generated. Because of integrated with three dimensional CAD, specification of boundary conditions and design variables can be finished based on the three dimensional CAD model, so user need not deal with nodal and element of finite model in the procedure of forming finite model and specifying mathematical problem for optimization. This paper introduces a new method how to insert the frequency sensitivity analysis process into the structural analysis program, integrate mathematical optimization method and design structure based frequency optimization. The program is applied to the optimal design of actual engineering. The results are acceptable.