To address the issue of excessive dynamic stress in the external accessory equipment of an aero - engine and its mounting bracket, a corresponding vibration isolation system was designed. First, considering the significant mass eccentricity of the equipment, the mass loads at each support point for the irregular installation were calculated through decoupling based on the torque balance equation. The natural frequency of the system was determined in accordance with classical vibration theory and the load characteristics of the engine, and the stiffness of each support point was calculated. Subsequently, a finite - element simulation model of the vibration isolation system was established. A silicone rubber vibration isolator was designed and optimized via simulation to achieve equal stiffness in three directions. Finally, the vibration isolation system was designed, fabricated, and experimentally verified on a vibration test bench. The research results show that the designed vibration isolation system can reduce the maximum dynamic stress of the bracket structure from 757.4 MPa to 127.1 MPa, meeting the strength design limit. Experimental verification indicates that the vibration isolation system exhibits good equal - stiffness performance in three directions, with a maximum error of 9.4% between the simulated and experimental values of the natural frequency. This resolves the strength design issue of the external accessory equipment and offers guidance for similar vibration isolation designs.