Abstract: The lecture series delivered by East German expert Hermann Rader at Tongji University from 1957 to 1958 represents a valuable case of international planning knowledge transfer in the early modernization of urban planning in China. Drawing on extensive primary materials from the Archives of Bauhaus University Weimar and other archival institutions, this paper systematically reviews the origins, content, and academic impact of Rader's lectures in China. Although the lectures were hosted by universities, their influence extended far beyond teaching. By introducing rigorous historical, theoretical, and scientific methodologies, Rader profoundly influenced and shaped the academic paths of Chinese urban planning scholars such as Dong Jianhong, Ruan Yisan, and Geng Yuxiu. Through planning practices in Shanghai and Hefei, the lectures also contributed to the formation of the Hefei Model, which integrated international experience with local realities. They thus left a lasting imprint on the modernization and localization of urban planning in China. The teaching and exchanges of foreign urban planning experts in the early PRC were not a simple one-way transmission of knowledge; they constituted a process of two-way empowerment and showed a dual, interactive mechanism of influence.