East Asian Core Observatory Association (EACOA), consisted of four core observatories in East Asia: National Astronomical Observatories, Chinese Academy of Sciences (NAOC), National Astronomical Observatory of Japan (NAOJ), Korea Astronomy and Space Science institute (KASI), and Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), is formed to foster and coordinate collaborations between the major astronomical observatories in the region. The mission of East Asian Core Observatory Association includes: 1. Development of alliance program in research, instruments and telescope construction, 2. Coordination of the exchange and use of observation instrumental and other resources within East Asia, 3. Talent exchange (especially the young astronomers) program, 4. Coordination of conference arrangement and other academic activities to facilitate the cooperation in astronomy research in East Asia, 5. Setting the developmental goal of East Asian Core Observatory Association and 6. Annual directors' meeting to ensure the effective achievement of the scientific cooperation envisaged by East Asian Core Observatory Association. As for China, Purple Mountain Observatory (PMO) and Shanghai Astronomical Observatory (SHAO) are also the members of EACOA together with NAOC.