Academic mobility is becoming a tread in academic life and a professional development globally, regionally and nationally. This article makes use of a case university--Peking University (PKU)--as an analytical approach to explore how and why academic mobility can happen in China's research universities. The author first presents an overview of the academic mobility at PKU from a historical perspective, and then describes the changing status quo of its academic mobility that has undergone for three decades. In the third part, the author analyzes and discusses the outcome made by the academic mobility from both positive and negative sides. In the end, the author notes that academic mobility is one among the best ways to internationalize China's research universities, including PKU.