Abstract: To address the fracture failure of the mounting lugs of the power splitter-coupler assembly of an airborne conformal antenna aperture during random vibration, failure mechanism analysis of the fault phenomenon is carried out, and the correctness of the failure mechanism is verified via numerical simulation and environmental tests. Collaborative optimization design of the structure and process is performed for the power splitter-coupler assembly based on the failure mechanism. The strength safety margin of the mounting lugs and fastening screws of the optimized assembly under random vibration conditions is checked by combining numerical simulation with theoretical calculation, and the effectiveness of the optimization measures is validated. It is concluded from the research that over-constrained installation with multiple mounting planes suffers matching constraint of flatness and perpendicularity, and the mounting clearances shall be reduced by adopting clearance adjusting shims. The extended mounting lug structure should be avoided as far as possible in the structural design of airborne equipment. If such a structure has to be adopted due to constraints including layout and dimensions, the strength safety margin of the lugs should be improved as much as possible on the premise that mass indicators are satisfied.