EAST tokamak is designed on the basis of the latest tokamak achievements of the last century, aiming at the world fusion research forefront. Its mission is to conduct fundamental physics and engineering researche at advanced tokamak fusion reactors with a steady, safe and high performance, to provide a scientific base for experimental reactor design and construction, and to promote the development of plasma physics and related disciplines and technologies. EAST construction and physics research will provide direct experience for the construction of International Thermonuclear Experimental Reactor project (ITER), and play a leading role in high-performance steady-state plasma physics research in the world, and ultimately contribute to the development of ITER and the fusion energy. Compared with ITER, although smaller, EAST is similar to ITER in shape and equilibrium, yet more flexible.