Aerodynamic performance and stealth capability are two critical objectives in the design of modern unmanned combat air vehicles （UCAVs）. This study develops parametric geometric models of the UCAV airframe， inlet， and nozzle through secondary development of CAD software， and conducts aerodynamic numerical simulations of integrated internal and external flow coupling using a 1D engine model. An aerodynamic-stealth integrated optimization framework is implemented through design of experiments （DoE） and surrogate modeling techniques for the UCAV airframe， inlet and exhaust system. The results demonstrate that the proposed optimization framework achieves significant improvements in both aerodynamic and stealth performance， validating its effectiveness in multi-objective aerodynamic-stealth optimization for aircraft with highly-integrated airframe-propulsion configurations. Furthermore， this methodology shows promising potential for accelerating design iterations and reducing developmental expenditures.