Abstract: If we take “the southeast mutual protection” as an independent historical theme of key importance, and even take Boxer Movement as the prelude of “the southeast mutual protection”, and take the latter as a kernel subject of the transformation of a convergence of the ancient and the modern, and China and the west in modern China, then, “the southeast mutual protection” has not only a legal significance of “quasi-international law treaty”. It is also related to a fundamental reform of political system, no less than a institutional innovation with active result which is seldom-seen in China’s early-modern state construction and transformation. It paves the way for late-Qing Dynasty new politics and the state transformation, and it contains a legal-political logic which has a referential significance even in today