The source of China's authority is its legislative body, which is the only one capable of coordinating, using and managing the country's constitution in an authoritarian and controlling manner.
This authority is characterized by the communist government, which has total control of the country and can even manipulate the laws, rules and guidelines of the constitution at will, as long as its authority is not weakened.
The source of political legitimacy in that country is its constitution, which allows the full power of the communist government and prohibits freedom and political diversity in the country, concentrating all government power in the hands of a single party.
During 120 years of management this has changed little, however, even in the midst of absolute control, the population has managed from time to time to turn against this regime and order changes. This popular pressure can even promote small changes that happen over time.