As a new-generation propulsion system, the adaptive cycle engine (ACE) requires dynamic couple of performance, aerodynamics, structure, and strength across wide operational conditions. Traditional aero-engine design typically adopts disciplinary sequential optimization, which suffers from long design cycles, poor interdisciplinary couple, and multi-component balanced designing difficulties, urgently demanding breakthroughs in multidisciplinary coupled design technologies. A multidisciplinary coupled design method for ACE was developed by establishing an efficient coupling model integrating engine performance calculation, size/weight estimation, and flowpath design. The “Difficulty Coefficient Balancing Method” was introduced to dynamically adjust component efficiencies, achieving collaborative design in multi-component. Based on the coupled model under multiple constraints, parameter sensitivity analysis was conducted to investigate the multidisciplinary transmission paths and coupling effects of key parameters including component efficiency, flowpath dimensions, and structural loads. Results indicate: A 1% increase in turbine inlet temperature raises thrust, specific fuel consumption, total length, and total weight by 0.96%, 1.06%, 0.22%, and − 0.3% respectively; A 1% increase in the pressure ratio of compression components causes load coefficient variations of − 1.21 to 1.75%; A 1% increase in turbine load coefficient reduces high/low-pressure turbine weights by 1.28% and 0.79%, while increasing total length by 0.59% and 0.6% respectively. Through the coupled model, this method enables transparent mapping of design parameters to multidisciplinary characteristics, breaks through the single-disciplinary limitations of traditional parameter sensitivity analysis, significantly improves the equilibrium of multi-component matching, and enhances ACE design efficiency.