Abstract: During the compilation of territorial spatial master plans, the projected population size in most cities remains inflated. The aggregate population size stated in municipal master plans often exceeds the population size set in provincial plans, producing a systematic upward distortion in the transmission of population indicators. At the same time, indicators such as per capita construction land cannot be matched with population figures and are therefore often regarded as nominal values. This paper argues that these phenomena arise from old modes of thinking within a new planning system: a biased understanding of the connotation of population size, which equates it with statistical population; an insufficient understanding of the systemic nature of territorial spatial planning, which leads to a simple emphasis on consistency across levels; and the limited adaptability of static planning to dynamic change, especially the neglect of dynamic flows. On this basis, the paper proposes that the setting of population size should adapt to the new system by distinguishing the policy meanings of population size at different planning levels, abandoning the pursuit of exact numerical correspondence, and optimizing human-land relations through refined management. These reflections are expected to provide references for improving the compilation of plans at different levels and of different types, refining the data logic of the one-map system, and enhancing the refined governance capacity of planning.