The future operational environment imposes higher and more comprehensive requirements for the performance of fighters, calling for deeper integration between fighter airframe and engine and closer collaborative design during fighter research and development. Building on theories and practices for optimum airframe-engine integration in fighter design in the past decades, this paper proposes a collaborative airframe-engine design concept. Through an analysis of the combat requirements of Penetrating Counter Air (PCA) and other operational concepts, this paper then presents the essential capabilities of high performance fighters and looks into the requirements of future-oriented collaborative airframe-engine design. The key technologies concerning flight performance, stealth characteristics, flight control and aircraft energy are discussed, and the possible implementation approaches and suggestions for design and research are also provided.