Abstract: In order to improve the dynamic performance of airborne electro-optical platform and diminish the negative effect of vibration environment on image quality, a topology optimization based on the variable density theory is studied. In the topology optimization of airborne electro-optical platform, the minimum combined compliance index is taken as an objective function and the fundamental frequency not less than a specified value as the constraint. And the stiffness，strength and modal performance of the inner frame structure before and after optimization are compared and analyzed. The results show that the static and dynamic characteristics are improved tremendously after optimization under the condition of the inner frame weight loss 8%, the maximum deformation dropped from 0.058 mm to 0.016 mm, the maximal stress reduces from 16.3 MPa to 2.7 MPa，and the fundamental frequency increases from 131 Hz to 213 Hz. In the case of reducing weight as well as reduce the maximum deformation of the structure effectively, the engine performance is improved. At last, the topology optimization result is verified by vibration test. This topology optimization technology will provide efficient help to the later design of electro-optical platform.

Key words: mechanical design;topology optimization;electro-optical platform;variable density method;finite element analysis