Space mission design software spans the entire lifecycle of space missions and is regarded as the cornerstone of the aerospace industrial software system. Leveraging nearly three decades of technical expertise in the field of manned spaceflight, the research team from the National University of Defense Technology initiated the development of the indigenous software ATK (Aerospace Tool Kit) in 2020. By the end of 2024, the ATK 3.0 version was officially released, encompassing five major categories and 21 functional modules, including standard platform, visibility and coverage analysis, mission analysis, orbital design, and secondary development. The development of ATK has been deeply and continuously supported by China’s Manned Spaceflight Program, pioneering a collaborative research and development model characterized by "engineering-driven demand + centralized academic development." This software has had a significant impact in aerospace engineering, space security, and academic education, marking a solid first step toward replacing STK (Systems Tool Kit). This paper reviews the development history of ATK, elaborates on its functional features, and focuses on analyzing its breakthroughs in core technologies such as large-scale software architecture design, computational kernel development, and orbital maneuver planning. While ATK faces challenges in enhancing its functionality and building its application ecosystem, the paper outlines its future development roadmap and strategic objectives .