By using the self-manufactured special processing equipment, the inner frame of a unmanned airborne optoelectronic stabilization platform is fabricated by the aluminum matrix composites with high volume fraction (55%～57%) SiC particles based on a pressureless infiltration technology. Benefiting from the composite's good mechanical properties, such as ultra-high modulus (the Young’s modulus is 213 GPa and the specific modulus is approximately three times of those of Al, Ti, and steel), low thermal expansion coefficient and very high thermal conductivity(235 W/m·K), the inner frame has decreased the maximum deformation by 60% and increased the fundamental frequency by 65% as compared with those of aluminum alloy materials,respectively. Therefore, a significant lightening effect is achieved and the thermal control load is also reduced. The test result indicates that the stable accuracy of the system achieves 20 μrad. The research applies the SiC/Al composites to airborne photoelectric platforms for the first time,which makes a effective exploration for the new aviation material's application.