The legacies of Sir Robert Hart and the Chinese Maritime Customs Service have been characterised by a variety of theories in modern China, ranging from Cantonisation, imperium in imperio, synarchy, impactresponse, tradition-modernity, revolutionary Marxism, informal empire, institutional breakthrough, etc. The controversy demonstrates the wide gap between the ways in which the theories and histories of Hart and the CMCS have been told and remembered in China, on the one hand, and in the West, on the other hand, in the twentieth century. The reconstruction of the legacies of Sir Robert and the CMCS enriches the theoretical ingredients bridging Chinese and Western scholars' different theories about modern China. The theorization of modern China was an evolutionary process which combines different groups of scholars' memories, experiences and histories. This article aims to examine how theories were generated from the research on the CMCS, how these theories argue against each other and how these debates generate new theories.