Abstract: The multi-objective optimization design of a triaxial vibration fixture is made through a mathematical model with the double objective optimization to maximize the first-order natural frequency of the fixture at a minimal weight. Three structural dimensions that significantly affect the dynamic performance of the fixture are chosen as the design variables under the constraint of the structural boundaries and the fixture mass. By combining the simulation with the SolidWorks and the ANSYS Workbench, and with the multi-goal genetic algorithm, a desirable optimization result is obtained, where the first-order natural frequency rises by 7.4% with a mass reduction of 20.1% at the same time. It is shown that the co-simulation technology and the optimization design method described in this paper are effective, and may also provide some reference for the optimization design of similar products.