Abstract: Rocket-based combined cycle (RBCC) engines, as promising propulsion systems for next-generation aerospace vehicles, have garnered significant attention due to their broad operational Mach range and potential for reusability. This paper systematically examines the multi-source environmental loads experienced by RBCC engines during mode transitions—ejector, subsonic combustion, supersonic combustion, and pure rocket modes—by analyzing their composite thermodynamic cycles and operational characteristics. The study emphasizes the adaptability of RBCC engines in various mission profiles, including two-stage-to-orbit systems, air-launch platforms, and highly maneuverable cruise missiles. To facilitate low-cost implementation, it explores key technological pathways such as integrated structural design, material system optimization, full-scale engine strength assessment, mode transition strategies, and propellant innovation. The findings offer theoretical guidance for the adaptive design, engineering realization, and practical deployment of RBCC engines.