Among China’s unresolved frontier questions, the South China Sea (SCS) has become the most complex and troubled, and arguably the most significant and disconcerting. The economic and security stakes are high and the stake-holding states are numerous and diverse. Mainstream medias and a substantial body literature have paid active attention to islands sovereignty and maritime demarcation from the perspective of legal theory and historical geography. In the same vein, there is another noticeable phenomenon that, along with the continuously maritime incidents involving regional fishermen, the diplomatic and security tensions between China and its neighbours are trapped into a vicious cycle. This paper provides a perspective in which fishers’ activities constitute a willful agent that works in part to govern the course of the boundary dispute based on field research in Hainan Province. Drawing on Sack' notion of Human Territoriality, we focused on various forms of territorialities and territorial strategies practiced by the power of different subjects. The study shows that China's sovereignty over the SCS has been established in well-defined boundary (nine-dash), and is solidly grounded in history. However, the border and territorial politics in SCS is characterized by complexity and diversified participants since modern times, and the state, fishers and foreign powers have constituted a multi-scalar and multi-agent territorial structure, which has resulted in‘potential conflicts’among various types of territorialization that overlay one another. Furthermore, it is also equally important to note that fishermen are self-motivated actors whose ultimate goal is to make a living. Mobilizing the realist motivation of livelihood and the territorial tactics of cross-border mobilities, this paper suggest that fishers are seeking to reinforce the state objectives of boundary legitimization and defense of claimed waters. The analysis, however, also demonstrates an ambivalent nature of territoriality, with fishers muddling the state interventions through their own conduct and rationale. The government thus faces a delicate task of managing the fishing operation vis-a?-vis the boundary dispute.