Abstract: China's national governance is accomplished by spatially dividing the country into several types of governance units according to the nature of governance tasks and governance needs. Various governance units are generated, used and managed through "lines" (vertical functional departments) and "blocks" (hierarchical governments) and exhibit the current state embedded in the "line-block structure". The characteristics of "line-block structure" with "blocks" as the main body and "lines" as the supplement determine that the governance units are based on the substantive governance units and supplemented by the quasi-substantive and virtual governance units. The "blocks", the "lines" of vertical management and the "lines" under dual leadership have different choices for governance units according to different governance tasks. The "lines" of central ministries and commissions carry out classified management of administrative areas and functional area, not only reflecting the interaction between "lines" and "blocks" but also forming a new relationship between "lines" and "blocks". Analyzing the mutual embedment between the "line-block structure" and governance units can provide a new perspective for perceiving the role of governance units and the relationship between "lines" and "blocks".