The multi-social structure is a core element of modern Western civilization. It formed in medieval times. Its shape mainly manifested in the dual power system , pluralism and multi-legal system of the power of the main aspects. Its main feature is a kind of the contractual relationship of confrontation and cooperate around The Subjective Rights. The formation and development depends on three major traditions, that the Germanic tradition, Roman ruins and Christian thought. As a kind of the social culture, it is a social structure of pluralism, the birth of modern constitutional democracy in Western Europe, gave birth to ensure the formation of the legal system of the market economy, so early into a modern Western society.