Abstract: The core ideas and concepts of educational system science are introduced, aiming to answer some core educational research questions with systems science approach, especially scientific research methods and system thinking． With a road map starting from accomplished projects to on-going and envisioned research work and practices, the formation and development of educational system science, an emerging branch of both systems science and education are proposed． From the system science point of view, educational system is a system with multiple entities of diverse types connected via relationships of diverse types, with ideally an overall function to society, to help students learn so that they will be able to create and creatively use knowledge, or to appreciate the creation and creative use of knowledge． A system with multiple parts and relations with overall function is typical object of research interest of systems science． Thus, education does need systems science．