With expansion of globalization and increment of transnational corporations(TNCs), R&D internationalization becomes a key point when TNCs execute innovation activities. Through analyzing the citations among academic articles, this paper uses different kinds of main path analysis to discover two major development trajectories and four recent active sub-areas of R&D internationalization. By analyzing the nodes on the main path, we could understand the evolution of research topic in this academic field. This paper has extracted the most influential journals and researchers through g-index. In the end, we concluded that R&D internationalization related researches have already reached the maturity stage according to the S-curve analysis.