Regional separation is an important issue concerning the core interests of sovereign States, and it is also a long-standing issue in the international political field. The regional separation movement not only appeared in some old European countries, but also plagued many newly established countries after World War II, and with the development of globalization, many new forms appeared one after another. In this regard, some sovereign countries have adopted policies such as devolution to try to curb regional separation. Since the second half of the 20th century, in order to win the support of Scottish nationalists, the British Labor Party has continuously promised to decentralize Scotland. By 1999, the Scottish Parliament was established, but it failed to make Britain develop towards unity and stability, on the contrary, it contributed to the momentum of national separation in Scotland. By means of literature research, this paper studies the interaction of the devolution policy adopted by the British government, and the separation movement of Scotland, and finds that the devolution of Britain has brought more internal differences, while the Scottish National Party has successfully used the opportunity brought by devolution to create conditions for ethnic separation.