China Customs is a government agency that supervises and manages all arrivals in and departures from the Customs territory of the People's Republic of China. According to the Customs Law of the People's Republic of China and other relevant laws and regulations, China Customs mainly undertakes 4 essential tasks:
To control inward and outward means of transportation, goods and articles;
To collect Customs duties, taxes and related charges;
To combat smuggling;
To compile Customs statistics and handle other Customs matters.
Accordingly, China Customs mainly performs 7 functions: clearance operation, revenue collection, processing trade and bond operation, Customs statistics compilation, audit-based control, counter-smuggling and port management. 
