1 economic root-the need to maintain the feudal economic base. During the Spring and Autumn Period and the Warring States Period, the improvement of social productive forces led to the disintegration of the old relations of production, and Shang Yang's reform in Qin established the dominant position of feudal economy, which was manifested as a self-sufficient natural economy. It is a feudal individual small-scale peasant economy. This economic model needs a strong state power to safeguard national unity and social stability and ensure the production and reproduction of small-scale peasant economy. The emerging landlord class also needs to establish centralization to consolidate its dominant position, safeguard its political and economic interests and protect its land ownership. This feudal mode of production decided the establishment of centralization of authority.

2 social roots-the need to consolidate and maintain national unity. Qin learned the lesson of warlord regime's incompetence next week, and established autocratic centralization after national reunification, in order to eliminate local separatist forces and safeguard national unity.

3 ideological roots-Legalism laid the theoretical foundation. Since Shang Yang's political reform, the Qin Dynasty has always taken legalism as its ruling ideology. Han Feizi summed up a hundred theories and founded a complete set of centralized political theory, which laid a theoretical foundation for Qin Shihuang to establish autocratic centralization.