Drawing on a unique dataset that combines returnees' survey data and their information on research publications extracted from the Scopus database, this study systematically examines whether and how international doctoral mentorship for Chinese students in European countries promotes research collaboration before and upon the return of these Chinese PhDs to China. The results show that a considerable proportion of European-trained Chinese PhD returnees had co-authorship with their supervisors during their PhD study, and most of them maintained this research partnership after returning to China. In addition to the co-authorship during doctoral study, some individual characteristics (e.g., gender and marital status) and organizational factors (e.g., country of doctoral study and current work unit) were also found to contribute to international research collaboration upon the return to China of these Chinese PhD holders. This study sheds new light on the mobility and research collaboration of international students and provides policy implications for promoting Sino-foreign student exchange and research collaboration.