This article focuses on the communication between Southern dynasties of China and countries of the maritime silk road in the sixth century, via the perspective of Buddhist kingship, to discuss how the authority of Southern dynasties of China utilized the Buddhist kingship as a political and diplomatic idea to construct the capital Jiankang (建康) as the center of East Asia and developed the new and special international relations. The international trade and diplomatic communications were prosperous in the period of Southern dynasties of China and the capital Jiankang had become an important city on the maritime silk road. Under the development of Buddhist kingship of the Liang dynasty, the capital Jiankang almost had become a Buddhist sacred city and the Buddhist kingship of the Liang dynasty strongly affected the diplomatic communications between the countries of the maritime silk road. In the Chinese official records in the sixth century, Buddhism was the main motif in the diplomatic documents of the Southern dynasties of China and countries of the maritime silk road. These highly Buddhism-influenced diplomatic documents, were translated and retouched by the Chinese official government of Liang that the kingdom of Liang almost regarded as the ideal Buddhist empire in the eyes of the countries of the maritime silk road. It could illustrate the development of the Buddhist kingship of Liang dynasty. Also, it demonstrates that the official authority of Liang took advantage of establishing formal diplomatic relations with Buddhist ideas, through receiving the diplomatic recognition of being the sacred Buddhist empire, Liang succeeded in fulfilling the goal of being the heartland of China and East Asia.