In theory, the people of China have power. Each level of government (local, district, regional, and national) has elected officials with decision-making power.
In practice, the Chinese government is largely administrative. Real decision-making power lies in the hands of the Chinese people who are members of the Communist Party of China (CPC). A high standing within the CPC gives members power, with the most important individuals being the members of the Politburo (executive committee) and the general secretary or leader of the Communist Party.
The CPC has a similar organisational structure to the government. Although many CPC members are elected officials, e.g. in the parliament (the National People's Congress), it is membership of the CPC that matters.