The year 2015 is the 100th anniversary of Albert Einstein's presentation of the Theory of General Relativity. To celebrate the big event, the International Conference on Gravitation and Cosmology, and the fourth Galileo-Xu Guangqi Meeting will be held on May 4-8, 2015 at the Institute of Theoretical Physics, Chinese Academy of Sciences (ITP-CAS), Beijing, China, associated with the KITPC/ITP-CAS program “The Next Detectors for Gravitational Wave Astronomy” (April 6 to May 8, 2015). The goal of the two conferences is to bring the leading scientists working on gravitation, cosmology and relativistic astrophysics together, to review the current status and to present further directions in gravity, cosmology and relativistic astrophysics, and to promote relevant researches in China. Cosponsored by the State Key Laboratory of Theoretical Physics (SKLTP/ITP-CAS), Kavli Institute for Theoretical Physics China (KITPC/ITP-CAS), University of Chinese Academy of Sciences(UCAS), Chinese Society of Gravitation and Relativistic Astrophysics, International Center for Theoretical Physics-Asian Pacific and National Natural Sciences Foundation of China, Chinese Center for Advanced Science and Technology(CCAST), Yunnan Observatories, Chinese Academy of Sciences, Department of Astronomy, the University of Science and Technology of China, International College of University of Chinese Academy of Sciences (IC-UCAS)