Abstract: During the early 1850s, crews of Portuguese lorchas and the west coast junks gathered in Ningbo, engaging in activities such as convoying, plundering, and other businesses. The rise of two rival groups reshaped the maritime power structure within the coastal zone of Ningbo. The interaction between two groups was characterized by a gradual reshaping of their respective crews and the establishment of antagonistic groups defined by Cantonese and Portuguese. This led to frequent violent conflicts in the region. The subsequent intervention of British and American consular officials, combined with the deliberate Westernization of members and equipment by the Cantonese, led to a more complex evolution of the conflict. On the one hand, the evolution of the conflict between two sides was deeply constrained by the influence of foreign presence in China, reflecting the subtly exercised micro-level power. Conversely, British and American consular officials developed a set of disengagement mechanisms to insulate the foreign community in Ningbo from violent confrontations. This phenomenon illustrates the inherent flexibility of the treaty system in its early implementation, as it was adapted to local Chinese practices.