The national defense space architecture （NDSA） is the future space capability architecture of the United States， which aims to unify and integrate the next generation of the US space defense capabilities and seek space superiority. To clarify the key driving factors of NDSA， deepen the understanding and cognition of its essential core， and grasp the direction of future development trends， this paper sorts out the structure of the NDSA and analyzes the development plan and current situation. It focuses on the recent satellite deployment and technical research on the key transmission layer， tracking layer， supervision layer， and operational management layer. The development motivation is discussed from three dimensions of national competition， flexible development， and operational innovation. Finally， the paper gives relevant inspiration to the NDSA and related fields in China.