Abstract: The system architecture and signal processing technology of airborne early-warning (AEW) radar promote each other and evolve generation by generation. The driving force of the signal processing evolution comes from the requirement of the system and the guideline in the building of system architecture is to achieve the core processing ability optimally. In this paper, the characteristics of AEW radar's clutter spectrum in the space-frequency domain and space-range-frequency domain are analyzed firstly. Then, the evolution history of two generation architecture-PD and STAP is summarized. At last, based on the clutter and interference rejection problem AEW radar facing, three possible evolution ways of AEW radar's system architecture in the future are proposed.