Grass-roots governance is the cornerstone of national governance, which is directly related to national development and social stability. Territorial management is an important way of grass-roots governance in China and plays an important role in grass-roots governance. At present, problems such as overburden, power and responsibility imbalance and efficiency decline appear in grass-roots governance. The alienation of territorial management is the main reason. Specifically, territorial management has experienced excessive expansion in grass-roots governance. The generation and development of territorial management is the embodiment of the balance between the authority and effectiveness of national governance. It is indispensable in grass-roots governance. However, the excessive expansion also has a negative impact on grass-roots governance. Fuzzy governance under the isomorphic governmental responsibility is the motivation of territorial management expansion in grass-roots governance, while the fixity of administrative space, the resource regulation of functional departments and the directness of grass-roots government governance are the “trigger conditions” of territorial management expansion. Based on this, there is a dilemma of governance disorder in grass-roots governance, which is manifested in the overload of burden, the imbalance of rights and responsibilities and the weakening of functions. In the context of territorial management expansion, we can try to determine territorial responsibilities, build linkage mechanisms and build coordination systems through the coordination of vertical government levels, horizontal government agencies and block structures, so as to realize the optimization of grass-roots governance.