Xian did his Ph.D in Peking University. He had received support from the China Scholarship Council to study in the University of California, Santa Cruz for two years. After graduation, he worded as a postdoc in the Kavli Institute for Astronomy and Astrophysics in China, Max-Planck Institute for Gravitational Physics in Germany, and Pontificia Universidad Catolica de Chile. He is now an assistant professor in the Astronomy Department of the School of Physics.