Living structure is a mathematical structure, in which there are far more small substructures than large ones. Under the notion of living structure, city science is defined as the science, art, and technology of dealing with the acquisition, storage, processing, production, presentation, and dissemination of city information to help address three fundamental issues about a city: how it looks, how it works, and what it ought to be. It is a new kind of science, for it is built under the third view of space: space is neither lifeless nor neutral but a living structure capable of being more living or less living (Alexander 2002–2005, Jiang and Huang 2021). It is a new kind of science, for science as conventionally conceived is mainly about understanding how things are rather than what things ought to be. It is a new kind of science, for it is framed under the Whiteheadian organismic world view rather than the Cartesian mechanistic world view. The new kind of city science aims not only for better understanding city structure and dynamics (how cities are in other words), but also for better transforming modern cities and communities to become living or more living (what cities ought to be, so to speak), towards a sustainable society. In this presentation, he will begin with the three fundamental issues about a city, and present the concept of living structure, and its two fundamental laws: scaling law (Jiang 2015) and Tobler’s law (1970). He will argue and demonstrate why one structure is more living or more structurally beautiful than another, and briefly present a research agenda on the new kind of city science. He will further discuss about cross-disciplinary collaboration and cooperation in the future.