The treaty port system has undergone continuous expansion since the Opium War, with an increase in the number of treaty ports and a gradual extension of their geographical locations from the south-eastern coast to the western inland regions. In 1888, a British merchant secured funding of the Upper Yangtze steam navigation company to construct the “S.S. Kuling” in an effort to navigate the Upper Yangtze River and reach Chungking (Pinyin: Chongqing), thereby fulfilling the stipulation in the Chefoo Convention that mandated the opening of Chungking as a new treaty port. British diplomatic archives reveal that deceptive tactics were employed to obscure the unfitness of the Kuling for upper river navigation, while the Tsungli-Yamen actively advocated for the opening of Chungking. A re-examination of the Kuling project and its negotiation process elucidates the intricate relationships among China, foreign powers, central and local authorities, as well as officials and merchants during the expansion of the treaty port system. This investigation contributes to a deeper understanding of the treaty port system’s impact on local society and China’s distinctive modernization trajectory in the late 19th century.