<p>Why is Earth, among the eight planets in our solar system, the only habitable one? Over the 4.6-billion-year evolution of the solar system, why did Mars and Venus evolve so differently? Where did life originate, and how will Earth evolve in the future? These questions are not only central to planetary science in the 21st century but are also deeply connected to humanity’s fundamental understanding of its own existence and planetary habitability. Addressing these grand scientific challenges demands a systematic, multidimensional research approach. In the temporal dimension, we need to trace the early formation and evolution of terrestrial planets; in the spatial dimension, we need to analyze the layered structure of planets and the coupling between these layers; from a comparative perspective, we also need to explore the atmospheric characteristics of exoplanets and the influence of their host stars on habitability. Supported by the Chinese Academy of Sciences’ Strategic Priority Research Program on “Formation, Evolution, and Habitability of Terrestrial Planets,” we have taken planetary habitability as the main research theme and conducted systematic, in-depth studies on terrestrial planets by integrating multiple approaches, including extraterrestrial sample analysis, deep-space exploration data processing, and numerical and experimental simulation. This paper comprehensively summarizes the significant advancements made by the project over the past five years. It covers topics ranging from the early processes and environmental evolution of terrestrial planets to open planetary systems linked to the external space environment, and from Earth’s Moon to exoplanets. Key achievements include the first confirmation of a solid inner core on Mars, revealing its core-mantle differentiation under high-pressure and high-temperature conditions, and the discovery that the youngest lunar basalts originated from a non-KREEP, volatile-poor mantle source region, challenging the long-held traditional hypothesis that “volatile-rich material drives late-stage volcanism”—a textbook-level achievement. While summarizing the latest research advances, this paper also looks toward future directions. Significantly improving the capability for multi-layered, multi-parameter detection of planets, especially global planetary survey capabilities, and vigorously developing related techniques and research methods, particularly the application of cutting-edge technologies such as quantum technology and artificial intelligence, will be the key to achieving further major breakthroughs in planetary science. By sharing these research findings and insights, we aim to inspire more young people to pursue careers in planetary science—a field full of opportunities and challenges—thereby promoting the sustainable development of planetary science in China and over the world.</p>