In contrast to the historical assessment of modern medicine as an emanation of hegemonic European domination operating exclusively under its auspices and presumably diffused to the rest of the world, this dissertation offers a new approach to discovering the collision, collaboration, and compromise between the local Chinese and the Pastorians in China, by focusing on medical practices in the network of knowledge circulation and influences of material culture and social beliefs on knowledge formation. Drawing upon evidence from archives both in China and in France and investigating how the practices had been shaped within environmental, political, and socio-cultural constraints, it argues that Pastorism in China functioned as a special style of practice, marked by its emphasis on localism that was unique to China. On the one hand, Pastorians in China validated traditional medical practices, which relied upon the Chinese textual tradition, by providing scientific explanations based on toxicology, immunology, and pharmacology. Moreover, they learned and adapted on the ground, by incorporating local knowledge and accommodating local political circumstances and socio-cultural practices within their vaccination campaigns. On the other hand, they accounted for the acclimatization of local environmental specificities, pertaining to pathogens and animal species, in their vaccine production. These encounters and practices informed the colonial understanding of local meaning of public health, contagion, and immunity. Conversely, the ensuing knowledge reshaped the colonial medical practices and public health measures. The connections among the European Pastorians, Chinese practitioners of traditional medicine, and Chinese practitioners of Western medicine, as well as other colonial and international medical personnel and institutions, enabled multi-directional and transnational mobility that served as a fertile ground for mutual accommodation and created the contemporary medical landscape, which laid the foundation for modern integrative medicine and health care in the present day Chinese state.