Returned scholars are typical carriers of knowledge transfer and innovation. Based on the samples of 64 Chinese scientists returning from MIT and Stanford University, this paper analyses the impacts of their research experience in the United States on scientific research outputs and international collaborations after returning. The results show that the number of publications while doing study in the United States is positively correlated with the number after their returning, which means the scholars can extend their scientific productivity. Meanwhile, for those general disciplines like Nano technology, the scholars are willing to keep international research collaborations with their US mentors. On the contrary, for those scholars who have high quality publications, their collaboration intention is not strong. This paper presents new evidence for international knowledge transfer and innovation upon the migration of returned scholars.