Abstract: The establishment of the protective system of minority nationality for the League of Nations serves as the first attempt to deal, by way of the supervision and regulation of an international organization, with the conflict between ethnic groups, and also as the arrangement of main countries that is necessary to make to maintain postwar peace of the world driven by the national movement in the late 19th and early 20th centuries. Inheriting and developing the historical tradition of the European international society, this system distinguishes itself in confining to the Central and Eastern Europe, emphasizing the order priority, and possessing the great fragility due to the weakness of the organization itself.

Key words: protective system of minority nationality, relation between ethnic groups, the League of Nations